<?xml version="1.0" encoding="latin1" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">
<erlref>
<header>
<copyright>
<year>2000</year><year>2009</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
The contents of this file are subject to the Erlang Public License,
Version 1.1, (the "License"); you may not use this file except in
compliance with the License. You should have received a copy of the
Erlang Public License along with this software. If not, it can be
retrieved online at http://www.erlang.org/.
Software distributed under the License is distributed on an "AS IS"
basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
the License for the specific language governing rights and limitations
under the License.
</legalnotice>
<title>xref</title>
<prepared>Hans Bolinder</prepared>
<responsible>nobody</responsible>
<docno></docno>
<approved>nobody</approved>
<checked>no</checked>
<date>2000-08-15</date>
<rev>PA1</rev>
<file>xref.sgml</file>
</header>
<module>xref</module>
<modulesummary>A Cross Reference Tool for analyzing dependencies between functions, modules, applications and releases.</modulesummary>
<description>
<p>Xref is a cross reference tool that can be used for finding
dependencies between functions, modules, applications and
releases.
</p>
<p>Calls between functions are either <marker id="local_call"></marker>
<em>local calls</em> like <c>f()</c>, or <marker id="external_call"></marker>
<em>external calls</em> like
<c>m:f()</c>. <marker id="module_data"></marker>
<em>Module data</em>,
which are extracted from BEAM files, include local functions,
exported functions, local calls and external calls. By default,
calls to built-in functions (<term id="BIF"></term>) are ignored, but
if the option <c>builtins</c>, accepted by some of this
module's functions, is set to <c>true</c>, calls to BIFs
are included as well. It is the analyzing OTP version that
decides what functions are BIFs. Functional objects are assumed
to be called where they are created (and nowhere else). <marker id="unresolved_call"></marker>
<em>Unresolved calls</em> are calls to
<c>apply</c> or <c>spawn</c> with variable module, variable
function, or variable arguments. Examples are <c>M:F(a)</c>,
<c>apply(M, f, [a])</c>, and
<c>spawn(m, f(), Args)</c>. Unresolved calls are
represented by calls where variable modules have been replaced
with the atom <c>'$M_EXPR'</c>, variable functions have been
replaced with the atom <c>'$F_EXPR'</c>, and variable number of
arguments have been replaced with the number <c>-1</c>. The
above mentioned examples are represented by calls to
<c>'$M_EXPR':'$F_EXPR'/1</c>, <c>'$M_EXPR':f/1</c>, and
<c>m:'$F_EXPR'/-1</c>. The unresolved calls are a subset of the
external calls.
</p>
<warning>
<p>Unresolved calls make module data incomplete, which
implies that the results of analyses may be invalid.</p>
</warning>
<p><em>Applications</em> are collections of modules. The
modules' BEAM files are located in the <c>ebin</c>
subdirectory of the application directory. The name of the
application directory determines the name and version of the
application.
<em>Releases</em> are collections of applications
located in the <c>lib</c> subdirectory of the release directory.
There is more to read about applications and releases in the
Design Principles book.
</p>
<p> <marker id="xref_server"></marker>
<em>Xref servers</em> are identified
by names, supplied when creating new servers. Each Xref server
holds a set of releases, a set of applications, and a set of
modules with module data. Xref servers are independent of each
other, and all analyses are evaluated in the context of one
single Xref server (exceptions are the functions <c>m/1</c> and
<c>d/1</c> which do not use servers at all). The <marker id="mode"></marker>
<em>mode</em> of an Xref server determines what module
data are extracted from BEAM files as modules are added to the
server. Starting with R7, BEAM files compiled with the option
<c>debug_info</c> contain so called <marker id="debug_info"></marker>
debug information, which is an abstract
representation of the code. In <c>functions</c> mode, which is
the default mode, function calls and line numbers are extracted
from debug information. In <c>modules</c> mode, debug
information is ignored if present, but dependencies between
modules are extracted from other parts of the BEAM files. The
<c>modules</c> mode is significantly less time and space
consuming than the <c>functions</c> mode, but the analyses that
can be done are limited.
</p>
<p>An <marker id="analyzed_module"></marker>
<em>analyzed module</em> is a
module that has been added to an Xref server together with its
module data.
A <marker id="library_module"></marker>
<em>library module</em> is a
module located in some directory mentioned in the <marker id="library_path"></marker>
<em>library path</em>.
A library module is said to be used if some of its exported
functions are used by some analyzed module.
An <marker id="unknown_module"></marker>
<em>unknown module</em> is a
module that is neither an analyzed module nor a library module,
but whose exported functions are used by some analyzed module.
An <marker id="unknown_function"></marker>
<em>unknown function</em> is a
used function that is neither local or exported by any
analyzed module nor exported by any library module.
An <marker id="undefined_function"></marker>
<em>undefined function</em> is an externally used function that
is not exported by any analyzed module or library module. With
this notion, a local function can be an undefined function, namely
if it is externally used from some module. All unknown functions
are also undefined functions; there is a <seealso marker="xref_chapter#venn2">figure</seealso> in the
User's Guide that illustrates this relationship.
</p>
<p>Starting with R9C, the module attribute tag <c>deprecated</c>
can be used to inform Xref about <marker id="deprecated_function"></marker>
<em>deprecated functions</em> and
optionally when functions are planned to be removed. A few
examples show the idea:
</p>
<taglist>
<tag>-deprecated({f,1}).</tag>
<item>The exported function <c>f/1</c> is deprecated. Nothing is
said whether <c>f/1</c> will be removed or not.</item>
<tag>-deprecated({f,'_'}).</tag>
<item>All exported functions <c>f/0</c>, <c>f/1</c> and so on are
deprecated.</item>
<tag>-deprecated(module).</tag>
<item>All exported functions in the module are deprecated.
Equivalent to <c>-deprecated({'_','_'}).</c>.</item>
<tag>-deprecated([{g,1,next_version}]).</tag>
<item>The function <c>g/1</c> is deprecated and will be
removed in next version.</item>
<tag>-deprecated([{g,2,next_major_release}]).</tag>
<item>The function <c>g/2</c> is deprecated and will be
removed in next major release.</item>
<tag>-deprecated([{g,3,eventually}]).</tag>
<item>The function <c>g/3</c> is deprecated and will
eventually be removed.</item>
<tag>-deprecated({'_','_',eventually}).</tag>
<item>All exported functions in the module are deprecated and
will eventually be removed.</item>
</taglist>
<p>Before any analysis can take place, module data must be <em>set up</em>. For instance, the cross reference and the unknown
functions are computed when all module data are known. The
functions that need complete data (<c>analyze</c>, <c>q</c>,
<c>variables</c>) take care of setting up data automatically.
Module data need to be set up (again) after calls to any of the
<c>add</c>, <c>replace</c>, <c>remove</c>,
<c>set_library_path</c> or <c>update</c> functions.
</p>
<p>The result of setting up module data is the <marker id="call_graph"></marker>
<em>Call Graph</em>. A (directed) graph
consists of a set of vertices and a set of (directed) edges. The
edges represent <marker id="call"></marker>
<em>calls</em> (From, To)
between functions, modules, applications or releases. From is
said to call To, and To is said to be used by From. The vertices
of the Call Graph are the functions of all module data: local
and exported functions of analyzed modules; used BIFs; used
exported functions of library modules; and unknown functions.
The functions <c>module_info/0,1</c> added by the compiler are
included among the exported functions, but only when called from
some module. The edges are the function calls of all module
data. A consequence of the edges being a set is that there is
only one edge if a function is locally or externally used
several times on one and the same line of code.
</p>
<p>The Call Graph is <marker id="representation"></marker>
represented by
Erlang terms (the sets are lists), which is suitable for many
analyses. But for analyses that look at chains of calls, a list
representation is much too
slow. Instead the representation offered by the <c>digraph</c>
module is used. The translation of the list representation of
the Call Graph - or a subgraph thereof - to the <c>digraph</c>
representation does not
come for free, so the language used for expressing queries to be
described below has a special operator for this task and a
possibility to save the <c>digraph</c> representation for
subsequent analyses.
</p>
<p>In addition to the Call Graph there is a graph called the
<marker id="inter_call_graph"></marker>
<em>Inter Call Graph</em>. This is
a graph of calls (From, To) such that there is a chain of
calls from From to To in the Call Graph, and every From and To
is an exported function or an unused local function.
The vertices are the same as for the Call Graph.
</p>
<p>Calls between modules, applications and releases are also
directed graphs. The <marker id="type"></marker>
<em>types</em>
of the vertices and edges of these graphs are (ranging from the
most special to the most general):
<c>Fun</c> for functions; <c>Mod</c> for modules;
<c>App</c> for applications; and <c>Rel</c> for releases.
The following paragraphs will describe the different constructs
of the language used for selecting and analyzing parts of the
graphs, beginning with the <marker id="constants"></marker>
<em>constants</em>:
</p>
<list type="bulleted">
<item>Expression ::= Constants</item>
<item>Constants ::= Consts | Consts <c>:</c> Type | RegExpr</item>
<item>Consts ::= Constant | <c>[</c>Constant<c>,</c> ...<c>]</c>
| <c>{</c>Constant<c>,</c> ...<c>}</c></item>
<item>Constant ::= Call | Const</item>
<item>Call ::= FunSpec <c>-></c> FunSpec
| <c>{</c>MFA<c>,</c> MFA<c>}</c>
| AtomConst <c>-></c> AtomConst
| <c>{</c>AtomConst<c>,</c> AtomConst<c>}</c></item>
<item>Const ::= AtomConst | FunSpec | MFA</item>
<item>AtomConst ::= Application | Module | Release</item>
<item>FunSpec ::= Module <c>:</c> Function <c>/</c> Arity</item>
<item>MFA ::=
<c>{</c>Module<c>,</c> Function<c>,</c> Arity<c>}</c></item>
<item>RegExpr ::= RegString <c>:</c> Type
| RegFunc
| RegFunc <c>:</c> Type</item>
<item>RegFunc ::= RegModule <c>:</c> RegFunction <c>/</c> RegArity</item>
<item>RegModule ::= RegAtom</item>
<item>RegFunction ::= RegAtom</item>
<item>RegArity ::= RegString | Number | <c>_</c> | <c>-1</c></item>
<item>RegAtom ::= RegString | Atom | <c>_</c></item>
<item>RegString ::= - a regular expression, as described in the
<c>regexp</c> module, enclosed in double quotes -</item>
<item>Type ::= <c>Fun</c> | <c>Mod</c> | <c>App</c> | <c>Rel</c></item>
<item>Function ::= Atom</item>
<item>Application ::= Atom</item>
<item>Module ::= Atom</item>
<item>Release ::= Atom</item>
<item>Arity ::= Number | <c>-1</c></item>
<item>Atom ::= - same as Erlang atoms -</item>
<item>Number ::= - same as non-negative Erlang integers -</item>
</list>
<p>Examples of constants are: <c>kernel</c>, <c>kernel->stdlib</c>,
<c>[kernel, sasl]</c>, <c>[pg -> mnesia, {tv, mnesia}] : Mod</c>.
It is an error if an instance of <c>Const</c> does not match any
vertex of any graph.
If there are more than one vertex matching an untyped instance
of <c>AtomConst</c>, then the one of the most general type is
chosen.
A list of constants is interpreted as a set of constants, all of
the same type.
A tuple of constants constitute a chain of calls (which may,
but does not have to, correspond to an actual chain of calls of
some graph).
Assigning a type to a list or tuple of <c>Constant</c> is
equivalent to assigning the type to each <c>Constant</c>.
</p>
<p> <marker id="regexp"></marker>
<em>Regular expressions</em> are used as a
means to select some of the vertices of a graph.
A <c>RegExpr</c> consisting of a <c>RegString</c> and a type -
an example is <c>"xref_.*" : Mod</c> - is interpreted as those
modules (or applications or releases, depending on the type)
that match the expression.
Similarly, a <c>RegFunc</c> is interpreted as those vertices
of the Call Graph that match the expression.
An example is <c>"xref_.*":"add_.*"/"(2|3)"</c>, which matches
all <c>add</c> functions of arity two or three of any of the
xref modules.
Another example, one that matches all functions of arity 10 or
more: <c>_:_/"[1-9].+"</c>. Here <c>_</c> is an abbreviation for
<c>".*"</c>, that is, the regular expression that matches
anything.
</p>
<p>The syntax of <marker id="variable"></marker>
<em>variables</em> is
simple:
</p>
<list type="bulleted">
<item>Expression ::= Variable</item>
<item>Variable ::= - same as Erlang variables -</item>
</list>
<p>There are two kinds of variables: predefined variables and user
variables.
<marker id="predefined_variable"></marker>
<em>Predefined variables</em>
hold set up module data, and cannot be assigned to but only used
in queries.
<marker id="user_variable"></marker>
<em>User variables</em> on the other
hand can be assigned to, and are typically used for
temporary results while evaluating a query, and for keeping
results of queries for use in subsequent queries.
The predefined variables are (variables marked with (*) are
available in <c>functions</c> mode only):
</p>
<taglist>
<tag><c>E</c></tag>
<item>Call Graph Edges (*).</item>
<tag><c>V</c></tag>
<item>Call Graph Vertices (*).
</item>
<tag><c>M</c></tag>
<item>Modules. All modules: analyzed modules, used library
modules, and unknown modules.</item>
<tag><c>A</c></tag>
<item>Applications.</item>
<tag><c>R</c></tag>
<item>Releases.
</item>
<tag><c>ME</c></tag>
<item>Module Edges. All module calls.</item>
<tag><c>AE</c></tag>
<item>Application Edges. All application calls. </item>
<tag><c>RE</c></tag>
<item>Release Edges. All release calls.
</item>
<tag><c>L</c></tag>
<item>Local Functions (*). All local functions of analyzed modules.</item>
<tag><c>X</c></tag>
<item>Exported Functions. All exported functions of analyzed
modules and all used exported functions of library modules.</item>
<tag><c>F</c></tag>
<item>Functions (*).</item>
<tag><c>B</c></tag>
<item>Used BIFs. <c>B</c> is empty if <c>builtins</c> is
<c>false</c> for all analyzed modules.</item>
<tag><c>U</c></tag>
<item>Unknown Functions.</item>
<tag><c>UU</c></tag>
<item>Unused Functions (*). All local and exported functions of
analyzed modules that have not been used. </item>
<tag><c>XU</c></tag>
<item>Externally Used Functions. Functions of all modules -
including local functions - that have been used in some
external call.</item>
<tag><c>LU</c></tag>
<item>Locally Used Functions (*). Functions of all modules that have
been used in some local call.
</item>
<tag><c>LC</c></tag>
<item>Local Calls (*).</item>
<tag><c>XC</c></tag>
<item>External Calls (*).
</item>
<tag><c>AM</c></tag>
<item>Analyzed Modules.</item>
<tag><c>UM</c></tag>
<item>Unknown Modules.</item>
<tag><c>LM</c></tag>
<item>Used Library Modules.
</item>
<tag><c>UC</c></tag>
<item>Unresolved Calls. Empty in <c>modules</c> mode.
</item>
<tag><c>EE</c></tag>
<item>Inter Call Graph Edges (*).
</item>
<tag><c>DF</c></tag>
<item>Deprecated Functions. All deprecated exported
functions and all used deprecated BIFs.</item>
<tag><c>DF_1</c></tag>
<item>Deprecated Functions. All deprecated functions
to be removed in next version.</item>
<tag><c>DF_2</c></tag>
<item>Deprecated Functions. All deprecated functions
to be removed in next version or next major release.</item>
<tag><c>DF_3</c></tag>
<item>Deprecated Functions. All deprecated functions to be
removed in next version, next major release, or later.</item>
</taglist>
<p>These are a few <marker id="simple_facts"></marker>
facts about the
predefined variables (the set operators <c>+</c> (union) and
<c>-</c> (difference) as well as the cast operator
<c>(</c>Type<c>)</c> are described below):
</p>
<list type="bulleted">
<item><c>F</c> is equal to <c>L + X</c>.</item>
<item><c>V</c> is equal to <c>X + L + B + U</c>, where <c>X</c>,
<c>L</c>, <c>B</c> and <c>U</c> are pairwise disjoint (that
is, have no elements in common).</item>
<item><c>UU</c> is equal to <c>V - (XU + LU)</c>, where
<c>LU</c> and <c>XU</c> may have elements in common. Put in
another way:</item>
<item><c>V</c> is equal to <c>UU + XU + LU</c>.</item>
<item><c>E</c> is equal to <c>LC + XC</c>. Note that <c>LC</c>
and <c>XC</c> may have elements in common, namely if some
function is locally and externally used from one and the same
function.</item>
<item><c>U</c> is a subset of <c>XU</c>.</item>
<item><c>B</c> is a subset of <c>XU</c>.</item>
<item><c>LU</c> is equal to <c>range LC</c>.</item>
<item><c>XU</c> is equal to <c>range XC</c>.</item>
<item><c>LU</c> is a subset of <c>F</c>.</item>
<item><c>UU</c> is a subset of <c>F</c>. </item>
<item><c>range UC</c> is a subset of <c>U</c>.</item>
<item><c>M</c> is equal to <c>AM + LM + UM</c>, where <c>AM</c>,
<c>LM</c> and <c>UM</c> are pairwise disjoint. </item>
<item><c>ME</c> is equal to <c>(Mod) E</c>.</item>
<item><c>AE</c> is equal to <c>(App) E</c>.</item>
<item><c>RE</c> is equal to <c>(Rel) E</c>.</item>
<item><c>(Mod) V</c> is a subset of <c>M</c>. Equality holds
if all analyzed modules have some local, exported, or unknown
function.</item>
<item><c>(App) M</c> is a subset of <c>A</c>. Equality holds
if all applications have some module.</item>
<item><c>(Rel) A</c> is a subset of <c>R</c>. Equality holds
if all releases have some application.</item>
<item><c>DF_1</c> is a subset of <c>DF_2</c>.</item>
<item><c>DF_2</c> is a subset of <c>DF_3</c>.</item>
<item><c>DF_3</c> is a subset of <c>DF</c>.</item>
<item><c>DF</c> is a subset of <c>X + B</c>.</item>
</list>
<p>An important notion is that of <marker id="conversion"></marker>
<em>conversion</em> of expressions. The syntax of
a cast expression is:
</p>
<list type="bulleted">
<item>Expression ::= <c>(</c> Type <c>)</c> Expression</item>
</list>
<p>The interpretation of the cast operator depends on the named
type <c>Type</c>, the type of <c>Expression</c>, and the
structure of the elements of the interpretation of <c>Expression</c>.
If the named type is equal to the
expression type, no conversion is done. Otherwise, the
conversion is done one step at a time;
<c>(Fun) (App) RE</c>, for instance, is equivalent to
<c>(Fun) (Mod) (App) RE</c>. Now assume that the
interpretation of <c>Expression</c> is a set of constants
(functions, modules, applications or releases). If the named
type is more general than the expression type, say <c>Mod</c>
and <c>Fun</c> respectively, then the interpretation of the cast
expression is the set of modules that have at least one
of their functions mentioned in the interpretation of the
expression. If the named
type is more special than the expression type, say <c>Fun</c>
and <c>Mod</c>, then the interpretation is the set of all the
functions of the modules (in <c>modules</c> mode, the conversion
is partial since the local functions are not known).
The conversions to and from applications and releases
work analogously. For instance, <c>(App) "xref_.*" : Mod</c>
returns all applications containing at least one module
such that <c>xref_</c> is a prefix of the module name.
</p>
<p>Now assume that the interpretation of <c>Expression</c> is a
set of calls. If the named type is more general than the
expression type, say <c>Mod</c> and <c>Fun</c> respectively,
then the interpretation of the cast expression is the set of
calls (M1, M2) such that the interpretation of the
expression contains a call from some function
of M1 to some function of M2. If the named type is more special
than the expression type, say <c>Fun</c> and <c>Mod</c>, then
the interpretation is the set of all function calls
(F1, F2) such that the interpretation of the expression
contains a call (M1, M2) and F1 is
a function of M1 and F2 is a function of M2 (in <c>modules</c>
mode, there are no functions calls, so a cast to <c>Fun</c>
always yields an empty set). Again, the conversions to and from
applications and releases work analogously.
</p>
<p>The interpretation of constants and variables are sets, and
those sets can be used as the basis for forming new sets by the
application of <marker id="set_operator"></marker>
<em>set operators</em>.
The syntax:
</p>
<list type="bulleted">
<item>Expression ::= Expression BinarySetOp Expression</item>
<item>BinarySetOp ::= <c>+</c> | <c>*</c> | <c>-</c></item>
</list>
<p><c>+</c>, <c>*</c> and <c>-</c> are interpreted as union,
intersection and difference respectively: the union of two sets
contains the elements of both sets; the intersection of two sets
contains the elements common to both sets; and the difference of
two sets contains the elements of the first set that are not
members of the second set. The elements of the two sets must be
of the same structure; for instance, a function call cannot be
combined with a function. But if a cast operator can make the
elements compatible, then the more general elements are
converted to the less general element type. For instance,
<c>M + F</c> is equivalent to
<c>(Fun) M + F</c>, and <c>E - AE</c>
is equivalent to <c>E - (Fun) AE</c>. One more
example: <c>X * xref : Mod</c> is interpreted as the set of
functions exported by the module <c>xref</c>; <c>xref : Mod</c>
is converted to the more special type of <c>X</c> (<c>Fun</c>,
that is) yielding all functions of <c>xref</c>, and the
intersection with <c>X</c> (all functions exported by analyzed
modules and library modules) is interpreted as those functions
that are exported by some module <em>and</em> functions of
<c>xref</c>.
</p>
<p>There are also unary set operators:
</p>
<list type="bulleted">
<item>Expression ::= UnarySetOp Expression</item>
<item>UnarySetOp ::= <c>domain</c> | <c>range</c> | <c>strict</c></item>
</list>
<p>Recall that a call is a pair (From, To). <c>domain</c>
applied to a set of calls is interpreted as the set of all
vertices From, and <c>range</c> as the set of all vertices To.
The interpretation of the <c>strict</c> operator is the operand
with all calls on the form (A, A) removed.
</p>
<p>The interpretation of the <marker id="restriction"></marker>
<em>restriction operators</em> is a
subset of the first operand, a set of calls. The second operand,
a set of vertices, is converted to the type of the first operand.
The syntax of the restriction operators:
</p>
<list type="bulleted">
<item>Expression ::= Expression RestrOp Expression</item>
<item>RestrOp ::= <c>|</c></item>
<item>RestrOp ::= <c>||</c></item>
<item>RestrOp ::= <c>|||</c></item>
</list>
<p>The interpretation in some detail for the three operators:
</p>
<taglist>
<tag><c>|</c></tag>
<item>The subset of calls from any of the vertices.</item>
<tag><c>||</c></tag>
<item>The subset of calls to any of the vertices.</item>
<tag><c>|||</c></tag>
<item>The subset of calls to and from any of the vertices.
For all sets of calls <c>CS</c> and all sets of vertices
<c>VS</c>, <c>CS ||| VS </c> is equivalent to
<c>CS | VS * CS || VS</c>.</item>
</taglist>
<p> <marker id="graph_analyses"></marker>
Two functions (modules,
applications, releases) belong to the same strongly connected
component if they call each other (in)directly. The
interpretation of the <c>components</c> operator is the set of
strongly connected components of a set of calls. The
<c>condensation</c> of a set of calls is a new set of calls
between the strongly connected components such that there is an
edge between two components if there is some constant of the first
component that calls some constant of the second component.
</p>
<p>The interpretation of the <c>of</c> operator is a chain of
calls of the second operand (a set of calls) that passes throw
all of the vertices of the first operand (a tuple of
constants), in the given order. The second operand
is converted to the type of the first operand.
For instance, the <c>of</c> operator can be used for finding out
whether a function calls another function indirectly, and the
chain of calls demonstrates how. The syntax of the graph
analyzing operators:
</p>
<list type="bulleted">
<item>Expression ::= Expression GraphOp Expression</item>
<item>GraphOp ::= <c>components</c> | <c>condensation</c> | <c>of</c></item>
</list>
<p>As was mentioned before, the graph analyses operate on
the <c>digraph</c> representation of graphs.
By default, the <c>digraph</c> representation is created when
needed (and deleted when no longer used), but it can also be
created explicitly by use of the <c>closure</c> operator:
</p>
<list type="bulleted">
<item>Expression ::= ClosureOp Expression</item>
<item>ClosureOp ::= <c>closure</c></item>
</list>
<p>The interpretation of the <c>closure</c> operator is the
transitive closure of the operand.
</p>
<p>The restriction operators are defined for closures as well;
<c>closure E | xref : Mod</c> is
interpreted as the direct or indirect function calls from the
<c>xref</c> module, while the interpretation of
<c>E | xref : Mod</c> is the set of direct
calls from <c>xref</c>.
If some graph is to be used in several graph analyses, it saves
time to assign the <c>digraph</c> representation of the graph
to a user variable,
and then make sure that every graph analysis operates on that
variable instead of the list representation of the graph.
</p>
<p>The lines where functions are defined (more precisely: where
the first clause begins) and the lines where functions are used
are available in <c>functions</c> mode. The line numbers refer
to the files where the functions are defined. This holds also for
files included with the <c>-include</c> and <c>-include_lib</c>
directives, which may result in functions defined apparently in
the same line. The <em>line operators</em> are used for assigning
line numbers to functions and for assigning sets of line numbers
to function calls.
The syntax is similar to the one of the cast operator:
</p>
<list type="bulleted">
<item>Expression ::= <c>(</c> LineOp<c>)</c> Expression</item>
<item>Expression ::= <c>(</c> XLineOp<c>)</c> Expression</item>
<item>LineOp ::= <c>Lin</c> | <c>ELin</c> | <c>LLin</c> | <c>XLin</c></item>
<item>XLineOp ::= <c>XXL</c></item>
</list>
<p>The interpretation of the <c>Lin</c> operator applied to a set
of functions assigns to each function the line number where the
function is defined. Unknown functions and functions of library
modules are assigned the number 0.
</p>
<p>The interpretation of some LineOp operator applied to a
set of function calls assigns to each call the set of line
numbers where the first function calls the second function. Not
all calls are assigned line numbers by all operators:
</p>
<list type="bulleted">
<item>the <c>Lin</c> operator is defined for Call Graph Edges;</item>
<item>the <c>LLin</c> operator is defined for Local Calls.</item>
<item>the <c>XLin</c> operator is defined for External Calls.</item>
<item>the <c>ELin</c> operator is defined for Inter Call Graph Edges.</item>
</list>
<p>The <c>Lin</c> (<c>LLin</c>, <c>XLin</c>) operator assigns
the lines where calls (local calls, external calls) are made.
The <c>ELin</c> operator assigns to each call (From, To),
for which it is defined, every line L such that there is
a chain of calls from From to To beginning with a call on line
L.
</p>
<p>The <c>XXL</c> operator is defined for the interpretation of
any of the LineOp operators applied to a set of function
calls. The result is that of replacing the function call with
a line numbered function call, that is, each of the two
functions of the call is replaced by a pair of the function and
the line where the function is defined. The effect of the
<c>XXL</c> operator can be undone by the LineOp operators. For
instance, <c>(Lin) (XXL) (Lin) E</c> is
equivalent to <c>(Lin) E</c>.
</p>
<p>The <c>+</c>, <c>-</c>, <c>*</c> and <c>#</c> operators are
defined for line number expressions, provided the operands are
compatible. The LineOp operators are also defined for
modules, applications, and releases; the operand is implicitly
converted to functions. Similarly, the cast operator is defined
for the interpretation of the LineOp operators.
</p>
<p>The interpretation of the <marker id="count"></marker>
<em>counting operator</em> is the number of elements of a set. The operator
is undefined for closures. The <c>+</c>, <c>-</c> and <c>*</c>
operators are interpreted as the obvious arithmetical operators
when applied to numbers. The syntax of the counting operator:
</p>
<list type="bulleted">
<item>Expression ::= CountOp Expression</item>
<item>CountOp ::= <c>#</c></item>
</list>
<p>All binary operators are left associative; for instance,
<c>A | B || C</c> is equivalent to
<c>(A | B) || C</c>. The following is a list
of all operators, in increasing order of <marker id="precedence"></marker>
<em>precedence</em>:
</p>
<list type="bulleted">
<item><c>+</c>, <c>-</c></item>
<item><c>*</c></item>
<item><c>#</c></item>
<item><c>|</c>, <c>||</c>, <c>|||</c></item>
<item><c>of</c></item>
<item><c>(</c>Type<c>)</c></item>
<item><c>closure</c>, <c>components</c>, <c>condensation</c>,
<c>domain</c>, <c>range</c>, <c>strict</c></item>
</list>
<p>Parentheses are used for grouping, either to make an expression
more readable or to override the default precedence of operators:
</p>
<list type="bulleted">
<item>Expression ::= <c>(</c> Expression <c>)</c></item>
</list>
<p>A <marker id="query"></marker>
<em>query</em> is a non-empty sequence of
statements. A statement is either an assignment of a user
variable or an expression. The value of an assignment is the
value of the right hand side expression. It makes no sense to
put a plain expression anywhere else but last in queries. The
syntax of queries is summarized by these productions:
</p>
<list type="bulleted">
<item>Query ::= Statement<c>,</c> ...</item>
<item>Statement ::= Assignment | Expression</item>
<item>Assignment ::= Variable <c>:=</c> Expression
| Variable <c>=</c> Expression</item>
</list>
<p>A variable cannot be assigned a new value unless first removed.
Variables assigned to by the <c>=</c> operator are removed at
the end of the query, while variables assigned to by the
<c>:=</c> operator can only be removed by calls to
<c>forget</c>. There are no user variables when module data
need to be set up again; if any of the functions that make it
necessary to set up module data again is called, all user
variables are forgotten.
</p>
<p><em>Types</em></p>
<pre>
application() = atom()
arity() = int() | -1
bool() = true | false
call() = {atom(), atom()} | funcall()
constant() = mfa() | module() | application() | release()
directory() = string()
file() = string()
funcall() = {mfa(), mfa()}
function() = atom()
int() = integer() >= 0
library() = atom()
library_path() = path() | code_path
mfa() = {module(), function(), arity()}
mode() = functions | modules
module() = atom()
release() = atom()
string_position() = int() | at_end
variable() = atom()
xref() = atom() | pid() </pre>
</description>
<funcs>
<func>
<name>add_application(Xref, Directory [, Options]) -> {ok, application()} | Error</name>
<fsummary>Add the modules of an application.</fsummary>
<type>
<v>Directory = directory()</v>
<v>Error = {error, module(), Reason}</v>
<v>Options = [Option] | Option</v>
<v>Option = {builtins, bool()} | {name, application()} | {verbose, bool()} | {warnings, bool()}</v>
<v>Reason = {application_clash, {application(), directory(), directory()}} | {file_error, file(), error()} | {invalid_filename, term()} | {invalid_options, term()} | - see also add_directory -</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Adds an application, the modules of the application and <seealso marker="#module_data">module data</seealso> of the
modules to an <seealso marker="#xref_server">Xref server</seealso>.
The modules will be members of the application.
The default is to use the base name of the
directory with the version removed as application name, but
this can be overridden by the <c>name</c> option. Returns the
name of the application.
</p>
<p>If the given directory has a subdirectory named
<c>ebin</c>, modules (BEAM files) are searched for in that
directory, otherwise modules are searched for in the given
directory.
</p>
<p>If the <seealso marker="#mode">mode</seealso> of the Xref
server is <c>functions</c>, BEAM files that contain no
<seealso marker="#debug_info">debug information</seealso> are
ignored.
</p>
</desc>
</func>
<func>
<name>add_directory(Xref, Directory [, Options]) -> {ok, Modules} | Error</name>
<fsummary>Add the modules in a directory.</fsummary>
<type>
<v>Directory = directory()</v>
<v>Error = {error, module(), Reason}</v>
<v>Modules = [module()]</v>
<v>Options = [Option] | Option</v>
<v>Option = {builtins, bool()} | {recurse, bool()} | {verbose, bool()} | {warnings, bool()}</v>
<v>Reason = {file_error, file(), error()} | {invalid_filename, term()} | {invalid_options, term()} | {unrecognized_file, file()} | - error from beam_lib:chunks/2 -</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Adds the modules found in the given directory and the <seealso marker="#module_data">modules' data</seealso>
to an <seealso marker="#xref_server">Xref server</seealso>.
The default is not to examine subdirectories, but if the option
<c>recurse</c> has the value <c>true</c>, modules are searched
for in subdirectories on all levels as well as in the given
directory.
Returns a sorted list of the names of the added modules.
</p>
<p>The modules added will not be members of any applications.
</p>
<p>If the <seealso marker="#mode">mode</seealso> of the Xref
server is <c>functions</c>, BEAM files that contain no
<seealso marker="#debug_info">debug information</seealso> are
ignored.
</p>
</desc>
</func>
<func>
<name>add_module(Xref, File [, Options]) -> {ok, module()} | Error</name>
<fsummary>Add a module.</fsummary>
<type>
<v>Error = {error, module(), Reason}</v>
<v>File = file()</v>
<v>Options = [Option] | Option</v>
<v>Option = {builtins, bool()} | {verbose, bool()} | {warnings, bool()}</v>
<v>Reason = {file_error, file(), error()} | {invalid_filename, term()} | {invalid_options, term()} | {module_clash, {module(), file(), file()}} | {no_debug_info, file()} | - error from beam_lib:chunks/2 -</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Adds a module and its <seealso marker="#module_data">module data</seealso> to an <seealso marker="#xref_server">Xref server</seealso>.
The module will not be member of any application.
Returns the name of the module.
</p>
<p>If the <seealso marker="#mode">mode</seealso> of the Xref
server is <c>functions</c>, and the BEAM file contains no
<seealso marker="#debug_info">debug information</seealso>,
the error message <c>no_debug_info</c> is returned.
</p>
</desc>
</func>
<func>
<name>add_release(Xref, Directory [, Options]) -> {ok, release()} | Error</name>
<fsummary>Add the modules of a release.</fsummary>
<type>
<v>Directory = directory()</v>
<v>Error = {error, module(), Reason}</v>
<v>Options = [Option] | Option</v>
<v>Option = {builtins, bool()} | {name, release()} | {verbose, bool()} | {warnings, bool()}</v>
<v>Reason = {application_clash, {application(), directory(), directory()}} | {file_error, file(), error()} | {invalid_filename, term()} | {invalid_options, term()} | {release_clash, {release(), directory(), directory()}} | - see also add_directory -</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Adds a release, the applications of the release, the
modules of the applications, and <seealso marker="#module_data">module data</seealso> of the
modules to an <seealso marker="#xref_server">Xref server</seealso>.
The applications will be members of the release,
and the modules will be members of the applications.
The default is to use the base name of the
directory as release name, but this can be overridden by the
<c>name</c> option. Returns the name of the release.
</p>
<p>If the given directory has a subdirectory named <c>lib</c>,
the directories in that directory are assumed to be
application directories, otherwise all subdirectories of the
given directory are assumed to be application directories.
If there are several versions of some application, the one
with the highest version is chosen.
</p>
<p>If the <seealso marker="#mode">mode</seealso> of the Xref
server is <c>functions</c>, BEAM files that contain no
<seealso marker="#debug_info">debug information</seealso> are
ignored.
</p>
</desc>
</func>
<func>
<name>analyze(Xref, Analysis [, Options]) -> {ok, Answer} | Error</name>
<fsummary>Evaluate a predefined analysis.</fsummary>
<type>
<v>Analysis = undefined_function_calls | undefined_functions | locals_not_used | exports_not_used | deprecated_function_calls | {deprecated_function_calls, DeprFlag} | deprecated_functions | {deprecated_functions, DeprFlag} | {call, FuncSpec} | {use, FuncSpec} | {module_call, ModSpec} | {module_use, ModSpec} | {application_call, AppSpec} | {application_use, AppSpec} | {release_call, RelSpec} | {release_use, RelSpec}</v>
<v>Answer = [term()]</v>
<v>AppSpec = application() | [application()]</v>
<v>DeprFlag = next_version | next_major_release | eventually</v>
<v>Error = {error, module(), Reason}</v>
<v>FuncSpec = mfa() | [mfa()]</v>
<v>ModSpec = module() | [module()]</v>
<v>Options = [Option] | Option</v>
<v>Option = {verbose, bool()}</v>
<v>RelSpec = release() | [release()]</v>
<v>Reason = {invalid_options, term()} | {parse_error, string_position(), term()} | {unavailable_analysis, term()} | {unknown_analysis, term()} | {unknown_constant, string()} | {unknown_variable, variable()}</v>
<v>Xref = xref()</v>
</type>
<desc>
<p> <marker id="analyze"></marker>
Evaluates a predefined analysis.
Returns a sorted list without duplicates of <c>call()</c> or
<c>constant()</c>, depending on the chosen analysis. The
predefined analyses, which operate on all <seealso marker="#analyzed_module">analyzed modules</seealso>, are
(analyses marked with (*) are available in <c>functions</c><seealso marker="#mode">mode</seealso> only):</p>
<taglist>
<tag><c>undefined_function_calls</c>(*)</tag>
<item>Returns a list of calls to <seealso marker="#undefined_function">undefined functions</seealso>.</item>
<tag><c>undefined_functions</c></tag>
<item>Returns a list of <seealso marker="#undefined_function">undefined functions</seealso>. </item>
<tag><c>locals_not_used</c>(*)</tag>
<item>Returns a list of local functions that have not been
locally used.</item>
<tag><c>exports_not_used</c></tag>
<item>Returns a list of exported functions that have not been
externally used.</item>
<tag><c>deprecated_function_calls</c>(*)</tag>
<item>Returns a list of external calls to <seealso marker="#deprecated_function">deprecated functions</seealso>.</item>
<tag><c>{deprecated_function_calls, DeprFlag}</c>(*)</tag>
<item>Returns a list of external calls to deprecated
functions. If <c>DeprFlag</c> is equal to
<c>next_version</c>, calls to functions to be removed in
next version are returned. If <c>DeprFlag</c> is equal to
<c>next_major_release</c>, calls to functions to be
removed in next major release are returned as well as
calls to functions to be removed in next version. Finally,
if <c>DeprFlag</c> is equal to <c>eventually</c>, all
calls to functions to be removed are returned, including
calls to functions to be removed in next version or next
major release.</item>
<tag><c>deprecated_functions</c></tag>
<item>Returns a list of externally used deprecated
functions.</item>
<tag><c>{deprecated_functions, DeprFlag}</c></tag>
<item>Returns a list of externally used deprecated
functions. If <c>DeprFlag</c> is equal to
<c>next_version</c>, functions to be removed in next
version are returned. If <c>DeprFlag</c> is equal to
<c>next_major_release</c>, functions to be removed in next
major release are returned as well as functions to be
removed in next version. Finally, if <c>DeprFlag</c> is
equal to <c>eventually</c>, all functions to be removed
are returned, including functions to be removed in next
version or next major release.</item>
<tag><c>{call, FuncSpec}</c>(*)</tag>
<item>Returns a list of functions called by some of the given
functions.</item>
<tag><c>{use, FuncSpec}</c>(*)</tag>
<item>Returns a list of functions that use some of the given
functions.</item>
<tag><c>{module_call, ModSpec}</c></tag>
<item>Returns a list of modules called by some of the given
modules.</item>
<tag><c>{module_use, ModSpec}</c></tag>
<item>Returns a list of modules that use some of the given
modules.</item>
<tag><c>{application_call, AppSpec}</c></tag>
<item>Returns a list of applications called by some of the given
applications.</item>
<tag><c>{application_use, AppSpec}</c></tag>
<item>Returns a list of applications that use some of the given
applications.</item>
<tag><c>{release_call, RelSpec}</c></tag>
<item>Returns a list of releases called by some of the given
releases.</item>
<tag><c>{release_use, RelSpec}</c></tag>
<item>Returns a list of releases that use some of the given
releases.</item>
</taglist>
</desc>
</func>
<func>
<name>d(Directory) -> [DebugInfoResult] | [NoDebugInfoResult] | Error</name>
<fsummary>Check the modules in a directory using the code path.</fsummary>
<type>
<v>Directory = directory()</v>
<v>DebugInfoResult = {deprecated, [funcall()]} | {undefined, [funcall()]} | {unused, [mfa()]}</v>
<v>Error = {error, module(), Reason}</v>
<v>NoDebugInfoResult = {deprecated, [mfa()]} | {undefined, [mfa()]}</v>
<v>Reason = {file_error, file(), error()} | {invalid_filename, term()} | {unrecognized_file, file()} | - error from beam_lib:chunks/2 -</v>
</type>
<desc>
<p>The modules found in the given directory are checked for
calls to <seealso marker="#deprecated_function">deprecated functions</seealso>, calls to <seealso marker="#undefined_function">undefined functions</seealso>,
and for unused local functions. The code path is used as
<seealso marker="#library_path">library path</seealso>.
</p>
<p>If some of the found BEAM files contain <seealso marker="#debug_info">debug information</seealso>, then those
modules are checked and a list of tuples is returned. The
first element of each tuple is one of:
</p>
<list type="bulleted">
<item><c>deprecated</c>, the second element is a sorted list
of calls to deprecated functions;</item>
<item><c>undefined</c>, the second element is a sorted list
of calls to undefined functions;</item>
<item><c>unused</c>, the second element is a sorted list of
unused local functions.</item>
</list>
<p>If no BEAM file contains debug information, then a list of
tuples is returned. The first element of each tuple is one
of:
</p>
<list type="bulleted">
<item><c>deprecated</c>, the second element is a sorted list
of externally used deprecated functions;</item>
<item><c>undefined</c>, the second element is a sorted list
of undefined functions.</item>
</list>
</desc>
</func>
<func>
<name>forget(Xref) -> ok</name>
<name>forget(Xref, Variables) -> ok | Error</name>
<fsummary>Remove user variables and their values.</fsummary>
<type>
<v>Error = {error, module(), Reason}</v>
<v>Reason = {not_user_variable, term()}</v>
<v>Variables = [variable()] | variable()</v>
<v>Xref = xref()</v>
</type>
<desc>
<p><c>forget/1</c> and <c>forget/2</c> remove all or some of
the <seealso marker="#user_variable">user variables</seealso> of an <seealso marker="#xref_server">xref server</seealso>.</p>
</desc>
</func>
<func>
<name>format_error(Error) -> Chars</name>
<fsummary>Return an English description of an Xref error reply.</fsummary>
<type>
<v>Error = {error, module(), term()}</v>
<v>Chars = [char() | Chars]</v>
</type>
<desc>
<p>Given the error returned by any function of this module,
the function <c>format_error</c> returns a descriptive string
of the error in English. For file errors, the function
<c>format_error/1</c> in the <c>file</c> module is called.</p>
</desc>
</func>
<func>
<name>get_default(Xref) -> [{Option, Value}]</name>
<name>get_default(Xref, Option) -> {ok, Value} | Error</name>
<fsummary>Return the default values of options.</fsummary>
<type>
<v>Error = {error, module(), Reason}</v>
<v>Option = builtins | recurse | verbose | warnings</v>
<v>Reason = {invalid_options, term()}</v>
<v>Value = bool()</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Returns the default values of one or more options.</p>
</desc>
</func>
<func>
<name>get_library_path(Xref) -> {ok, LibraryPath}</name>
<fsummary>Return the library path.</fsummary>
<type>
<v>LibraryPath = library_path()</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Returns the <seealso marker="#library_path">library path</seealso>.</p>
</desc>
</func>
<func>
<name>info(Xref) -> [Info]</name>
<name>info(Xref, Category) -> [{Item, [Info]}]</name>
<name>info(Xref, Category, Items) -> [{Item, [Info]}]</name>
<fsummary>Return information about an Xref server.</fsummary>
<type>
<v>Application = [] | [application()]</v>
<v>Category = modules | applications | releases | libraries</v>
<v>Info = {application, Application} | {builtins, bool()} | {directory, directory()} | {library_path, library_path()} | {mode, mode()} | {no_analyzed_modules, int()} | {no_applications, int()} | {no_calls, {NoResolved, NoUnresolved}} | {no_function_calls, {NoLocal, NoResolvedExternal, NoUnresolved}} | {no_functions, {NoLocal, NoExternal}} | {no_inter_function_calls, int()} | {no_releases, int()} | {release, Release} | {version, Version}</v>
<v>Item = module() | application() | release() | library()</v>
<v>Items = Item | [Item]</v>
<v>NoLocal = NoExternal = NoResolvedExternal, NoResolved = NoUnresolved = int()</v>
<v>Release = [] | [release()]</v>
<v>Version = [int()]</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>The <c>info</c> functions return information as a list of
pairs {Tag, term()} in some order about the state and the
<seealso marker="#module_data">module data</seealso> of an <seealso marker="#xref_server">Xref server</seealso>.
</p>
<p><c>info/1</c> returns information with the following tags
(tags marked with (*) are available in <c>functions</c>
mode only):</p>
<list type="bulleted">
<item><c>library_path</c>, the <seealso marker="#library_path">library path</seealso>;</item>
<item><c>mode</c>, the <seealso marker="#mode">mode</seealso>;</item>
<item><c>no_releases</c>, number of releases;</item>
<item><c>no_applications</c>, total number of applications
(of all releases);</item>
<item><c>no_analyzed_modules</c>, total number of <seealso marker="#analyzed_module">analyzed modules</seealso>;</item>
<item><c>no_calls</c> (*), total number of calls (in all
modules), regarding instances of one function call in
different lines as separate calls;</item>
<item><c>no_function_calls</c> (*), total number of <seealso marker="#local_call">local calls</seealso>, resolved <seealso marker="#external_call">external calls</seealso> and
<seealso marker="#unresolved_call">unresolved calls</seealso>;</item>
<item><c>no_functions</c> (*), total number of local and exported
functions;</item>
<item><c>no_inter_function_calls</c> (*), total number of
calls of the <seealso marker="#inter_call_graph">Inter Call Graph</seealso>.</item>
</list>
<p><c>info/2</c> and <c>info/3</c> return information about
all or some of the analyzed modules, applications, releases
or library modules of an Xref server.
The following information is returned for every analyzed module:</p>
<list type="bulleted">
<item><c>application</c>, an empty list if the module does
not belong to any application, otherwise a list of
the application name;</item>
<item><c>builtins</c>, whether calls to BIFs are included
in the module's data;</item>
<item><c>directory</c>, the directory where the
module's BEAM file is located;</item>
<item><c>no_calls</c> (*), number of calls, regarding
instances of one function call in different lines as
separate calls;</item>
<item><c>no_function_calls</c> (*), number of local
calls, resolved external calls and unresolved calls;</item>
<item><c>no_functions</c> (*), number of local and exported
functions;</item>
<item><c>no_inter_function_calls</c> (*), number of calls
of the Inter Call Graph;</item>
</list>
<p>The following information is returned for every application:</p>
<list type="bulleted">
<item><c>directory</c>, the directory where the
modules' BEAM files are located;</item>
<item><c>no_analyzed_modules</c>, number of analyzed
modules;</item>
<item><c>no_calls</c> (*), number of calls of the
application's modules, regarding instances of
one function call in different lines as separate calls;</item>
<item><c>no_function_calls</c> (*), number of local
calls, resolved external calls and unresolved calls of the
application's modules;</item>
<item><c>no_functions</c> (*), number of local and exported
functions of the application's modules;</item>
<item><c>no_inter_function_calls</c> (*), number of calls
of the Inter Call Graph of the
application's modules;</item>
<item><c>release</c>, an empty list if the application does not
belong to any release, otherwise a list of the release name;</item>
<item><c>version</c>, the application's version as
a list of numbers. For instance, the directory "kernel-2.6"
results in the application name <c>kernel</c> and the
application version [2,6]; "kernel" yields the name
<c>kernel</c> and the version [].</item>
</list>
<p>The following information is returned for every release:</p>
<list type="bulleted">
<item><c>directory</c>, the release directory;</item>
<item><c>no_analyzed_modules</c>, number of analyzed
modules;</item>
<item><c>no_applications</c>, number of applications;</item>
<item><c>no_calls</c> (*), number of calls of the
release's modules, regarding
instances of one function call in different lines as
separate calls;</item>
<item><c>no_function_calls</c> (*), number of local
calls, resolved external calls and unresolved
calls of the release's modules;</item>
<item><c>no_functions</c> (*), number of local and exported
functions of the release's modules;</item>
<item><c>no_inter_function_calls</c> (*), number of calls
of the Inter Call Graph of the release's modules.</item>
</list>
<p>The following information is returned for every library module:</p>
<list type="bulleted">
<item><c>directory</c>, the directory where the <seealso marker="#library_module">library module's</seealso> BEAM file is located.</item>
</list>
<p>For every number of calls, functions etc. returned by the
<c>no_</c> tags, there is a query returning the same number.
Listed below are examples of such queries. Some of the
queries return the sum of a two or more of the <c>no_</c>
tags numbers. <c>mod</c> (<c>app</c>, <c>rel</c>) refers to
any module (application, release).
</p>
<list type="bulleted">
<item>
<p><c>no_analyzed_modules</c></p>
<list type="bulleted">
<item><c>"# AM"</c> (info/1)</item>
<item><c>"# (Mod) app:App"</c>
(application)</item>
<item><c>"# (Mod) rel:Rel"</c> (release)</item>
</list>
</item>
<item>
<p><c>no_applications</c></p>
<list type="bulleted">
<item><c>"# A"</c> (info/1)</item>
</list>
</item>
<item>
<p><c>no_calls</c>. The sum of the number of resolved and
unresolved calls:</p>
<list type="bulleted">
<item><c>"# (XLin) E + # (LLin) E"</c> (info/1)</item>
<item><c>"T = E | mod:Mod, # (LLin) T + # (XLin) T"</c>
(module)</item>
<item><c>"T = E | app:App, # (LLin) T + # (XLin) T"</c>
(application)</item>
<item><c>"T = E | rel:Rel, # (LLin) T + # (XLin) T"</c>
(release)</item>
</list>
</item>
<item>
<p><c>no_functions</c>. Functions in library modules and
the functions <c>module_info/0,1</c> are not counted by
<c>info</c>. Assuming that <c>"Extra := _:module_info/\\"(0|1)\\" + LM"</c> has been evaluated, the
sum of the number of local and exported functions are:</p>
<list type="bulleted">
<item><c>"# (F - Extra)"</c> (info/1)</item>
<item><c>"# (F * mod:Mod - Extra)"</c> (module)</item>
<item><c>"# (F * app:App - Extra)"</c> (application)</item>
<item><c>"# (F * rel:Rel - Extra)"</c> (release)</item>
</list>
</item>
<item>
<p><c>no_function_calls</c>. The sum of the number of
local calls, resolved external calls and unresolved calls:</p>
<list type="bulleted">
<item><c>"# LC + # XC"</c> (info/1)</item>
<item><c>"# LC | mod:Mod + # XC | mod:Mod"</c> (module)</item>
<item><c>"# LC | app:App + # XC | app:App"</c> (application)</item>
<item><c>"# LC | rel:Rel + # XC | mod:Rel"</c> (release)</item>
</list>
</item>
<item>
<p><c>no_inter_function_calls</c></p>
<list type="bulleted">
<item><c>"# EE"</c> (info/1)</item>
<item><c>"# EE | mod:Mod"</c> (module)</item>
<item><c>"# EE | app:App"</c> (application)</item>
<item><c>"# EE | rel:Rel"</c> (release)</item>
</list>
</item>
<item>
<p><c>no_releases</c></p>
<list type="bulleted">
<item><c>"# R"</c> (info/1)</item>
</list>
</item>
</list>
</desc>
</func>
<func>
<name>m(Module) -> [DebugInfoResult] | [NoDebugInfoResult] | Error</name>
<name>m(File) -> [DebugInfoResult] | [NoDebugInfoResult] | Error</name>
<fsummary>Check a module using the code path.</fsummary>
<type>
<v>DebugInfoResult = {deprecated, [funcall()]} | {undefined, [funcall()]} | {unused, [mfa()]}</v>
<v>Error = {error, module(), Reason}</v>
<v>File = file()</v>
<v>Module = module()</v>
<v>NoDebugInfoResult = {deprecated, [mfa()]} | {undefined, [mfa()]}</v>
<v>Reason = {file_error, file(), error()} | {interpreted, module()} | {invalid_filename, term()} | {cover_compiled, module()} | {no_such_module, module()} | - error from beam_lib:chunks/2 -</v>
</type>
<desc>
<p>The given BEAM file (with or without the <c>.beam</c>
extension) or the file found by calling
<c>code:which(Module)</c> is checked for calls to <seealso marker="#deprecated_function">deprecated functions</seealso>, calls to <seealso marker="#undefined_function">undefined functions</seealso>,
and for unused local functions. The code path is used as
<seealso marker="#library_path">library path</seealso>.
</p>
<p>If the BEAM file contains <seealso marker="#debug_info">debug information</seealso>, then a
list of tuples is returned. The first element of each tuple
is one of:
</p>
<list type="bulleted">
<item><c>deprecated</c>, the second element is a sorted list
of calls to deprecated functions;</item>
<item><c>undefined</c>, the second element is a sorted list
of calls to undefined functions;</item>
<item><c>unused</c>, the second element is a sorted list of
unused local functions.</item>
</list>
<p>If the BEAM file does not contain debug information, then a
list of tuples is returned. The first element of each tuple
is one of:
</p>
<list type="bulleted">
<item><c>deprecated</c>, the second element is a sorted list
of externally used deprecated functions;</item>
<item><c>undefined</c>, the second element is a sorted list
of undefined functions.</item>
</list>
</desc>
</func>
<func>
<name>q(Xref, Query [, Options]) -> {ok, Answer} | Error</name>
<fsummary>Evaluate a query.</fsummary>
<type>
<v>Answer = false | [constant()] | [Call] | [Component] | int() | [DefineAt] | [CallAt] | [AllLines]</v>
<v>Call = call() | ComponentCall</v>
<v>ComponentCall = {Component, Component}</v>
<v>Component = [constant()]</v>
<v>DefineAt = {mfa(), LineNumber}</v>
<v>CallAt = {funcall(), LineNumbers}</v>
<v>AllLines = {{DefineAt, DefineAt}, LineNumbers}</v>
<v>Error = {error, module(), Reason}</v>
<v>LineNumbers = [LineNumber]</v>
<v>LineNumber = int()</v>
<v>Options = [Option] | Option</v>
<v>Option = {verbose, bool()}</v>
<v>Query = string() | atom()</v>
<v>Reason = {invalid_options, term()} | {parse_error, string_position(), term()} | {type_error, string()} | {type_mismatch, string(), string()} | {unknown_analysis, term()} | {unknown_constant, string()} | {unknown_variable, variable()} | {variable_reassigned, string()}</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Evaluates a <seealso marker="#query">query</seealso> in the
context of an <seealso marker="#xref_server">Xref server</seealso>, and returns the value of the last
statement. The syntax of the value depends on the
expression:
</p>
<list type="bulleted">
<item>A set of calls is represented by a sorted list without
duplicates of <c>call()</c>.</item>
<item>A set of constants is represented by a sorted list
without duplicates of <c>constant()</c>.</item>
<item>A set of strongly connected components is a sorted list
without duplicates of <c>Component</c>.</item>
<item>A set of calls between strongly connected components is
a sorted list without duplicates of <c>ComponentCall</c>.</item>
<item>A chain of calls is represented by a list of
<c>constant()</c>. The list contains the From vertex of every
call and the To vertex of the last call.</item>
<item>The <c>of</c> operator returns <c>false</c> if no chain
of calls between the given constants can be found.</item>
<item>The value of the <c>closure</c> operator (the
<c>digraph</c> representation) is represented by the atom
<c>'closure()'</c>.</item>
<item>A set of line numbered functions is represented by a sorted
list without duplicates of <c>DefineAt</c>.</item>
<item>A set of line numbered function calls is represented by
a sorted list without duplicates of <c>CallAt</c>.</item>
<item>A set of line numbered functions and function calls is
represented by a sorted list without duplicates of
<c>AllLines</c>.</item>
</list>
<p>For both <c>CallAt</c> and <c>AllLines</c> it holds that for
no list element is <c>LineNumbers</c> an empty list; such
elements have been removed. The constants of <c>component</c>
and the integers of <c>LineNumbers</c> are sorted and without
duplicates.
</p>
</desc>
</func>
<func>
<name>remove_application(Xref, Applications) -> ok | Error</name>
<fsummary>Remove applications and their modules.</fsummary>
<type>
<v>Applications = application() | [application()]</v>
<v>Error = {error, module(), Reason}</v>
<v>Reason = {no_such_application, application()}</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Removes applications and their modules and <seealso marker="#module_data">module data</seealso> from an <seealso marker="#xref_server">Xref server</seealso>.</p>
</desc>
</func>
<func>
<name>remove_module(Xref, Modules) -> ok | Error</name>
<fsummary>Remove analyzed modules.</fsummary>
<type>
<v>Error = {error, module(), Reason}</v>
<v>Modules = module() | [module()]</v>
<v>Reason = {no_such_module, module()}</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Removes <seealso marker="#analyzed_module">analyzed modules</seealso> and <seealso marker="#module_data">module data</seealso> from an <seealso marker="#xref_server">Xref server</seealso>.</p>
</desc>
</func>
<func>
<name>remove_release(Xref, Releases) -> ok | Error</name>
<fsummary>Remove releases and their applications and modules.</fsummary>
<type>
<v>Error = {error, module(), Reason}</v>
<v>Reason = {no_such_release, release()}</v>
<v>Releases = release() | [release()]</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Removes releases and their applications, modules and
<seealso marker="#module_data">module data</seealso> from an
<seealso marker="#xref_server">Xref server</seealso>.</p>
</desc>
</func>
<func>
<name>replace_application(Xref, Application, Directory [, Options]) -> {ok, application()} | Error</name>
<fsummary>Replace an application's modules.</fsummary>
<type>
<v>Application = application()</v>
<v>Directory = directory()</v>
<v>Error = {error, module(), Reason}</v>
<v>Options = [Option] | Option</v>
<v>Option = {builtins, bool()} | {verbose, bool()} | {warnings, bool()}</v>
<v>Reason = {no_such_application, application()} | - see also add_application -</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Replaces the modules of an application with other modules
read from an application directory. Release membership of the
application is retained. Note that the name of the
application is kept; the name of the given directory is not
used.
</p>
</desc>
</func>
<func>
<name>replace_module(Xref, Module, File [, Options]) -> {ok, module()} | Error</name>
<fsummary>Replace an analyzed module.</fsummary>
<type>
<v>Error = {error, module(), Reason}</v>
<v>File = file()</v>
<v>Module = module()</v>
<v>Options = [Option] | Option</v>
<v>Option = {verbose, bool()} | {warnings, bool()}</v>
<v>ReadModule = module()</v>
<v>Reason = {module_mismatch, module(), ReadModule} | {no_such_module, module()} | - see also add_module -</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Replaces <seealso marker="#module_data">module data</seealso> of an <seealso marker="#analyzed_module">analyzed module</seealso> with
data read from a BEAM file. Application membership of the
module is retained, and so is the value of the
<c>builtins</c> option of the module. An error is returned
if the name of the read module differs from the given
module.
</p>
<p>The <c>update</c> function is an alternative for updating
module data of recompiled modules.</p>
</desc>
</func>
<func>
<name>set_default(Xref, Option, Value) -> {ok, OldValue} | Error</name>
<name>set_default(Xref, OptionValues) -> ok | Error</name>
<fsummary>Set the default values of options.</fsummary>
<type>
<v>Error = {error, module(), Reason}</v>
<v>OptionValues = [OptionValue] | OptionValue</v>
<v>OptionValue = {Option, Value}</v>
<v>Option = builtins | recurse | verbose | warnings</v>
<v>Reason = {invalid_options, term()}</v>
<v>Value = bool()</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Sets the default value of one or more options.
The options that can be set this way are:</p>
<list type="bulleted">
<item><c>builtins</c>, with initial default value <c>false</c>;</item>
<item><c>recurse</c>, with initial default value <c>false</c>;</item>
<item><c>verbose</c>, with initial default value <c>false</c>;</item>
<item><c>warnings</c>, with initial default value <c>true</c>.</item>
</list>
<p>The initial default values are set when creating an <seealso marker="#xref_server">Xref server</seealso>.
</p>
</desc>
</func>
<func>
<name>set_library_path(Xref, LibraryPath [, Options]) -> ok | Error</name>
<fsummary>Set the library path and finds the library modules.</fsummary>
<type>
<v>Error = {error, module(), Reason}</v>
<v>LibraryPath = library_path()</v>
<v>Options = [Option] | Option</v>
<v>Option = {verbose, bool()}</v>
<v>Reason = {invalid_options, term()} | {invalid_path, term()}</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Sets the <seealso marker="#library_path">library path</seealso>. If the given path is a list of
directories, the set of <seealso marker="#library_module">library modules</seealso> is
determined by choosing the first module
encountered while traversing the directories in
the given order, for those modules that occur in more than
one directory. By default, the library path is an empty list.
</p>
<p>The library path <marker id="code_path"></marker>
<c>code_path</c> is
used by the functions
<c>m/1</c> and <c>d/1</c>, but can also be set explicitly.
Note however that the code path will be traversed once for
each used <seealso marker="#library_module">library module</seealso> while setting up module data.
On the other hand, if there are only a few modules that are
used by not analyzed, using <c>code_path</c> may be faster
than setting the library path to <c>code:get_path()</c>.
</p>
<p>If the library path is set to <c>code_path</c>, the set of
library modules is not determined, and the <c>info</c>
functions will return empty lists of library modules.</p>
</desc>
</func>
<func>
<name>start(NameOrOptions) -> Return</name>
<fsummary>Create an Xref server.</fsummary>
<type>
<v>Name = atom()()</v>
<v>XrefOrOptions = Xref | Options</v>
<v>Options = [Option] | Option</v>
<v>Option = {xref_mode, mode()} | term()</v>
<v>Return = {ok, pid()} | {error, {already_started, pid()}}</v>
</type>
<desc>
<p>Creates an <seealso marker="#xref_server">Xref server</seealso>.
The process may optionally be given a name.
The default <seealso marker="#mode">mode</seealso> is <c>functions</c>.
Options that are not recognized by Xref
are passed on to <c>gen_server:start/4</c>.</p>
</desc>
</func>
<func>
<name>start(Name, Options) -> Return</name>
<fsummary>Create an Xref server.</fsummary>
<type>
<v>Name = atom()()</v>
<v>Options = [Option] | Option</v>
<v>Option = {xref_mode, mode()} | term()</v>
<v>Return = {ok, pid()} | {error, {already_started, pid()}}</v>
</type>
<desc>
<p>Creates an <seealso marker="#xref_server">Xref server</seealso>
with a given name.
The default <seealso marker="#mode">mode</seealso> is <c>functions</c>.
Options that are not recognized by Xref
are passed on to <c>gen_server:start/4</c>.</p>
</desc>
</func>
<func>
<name>stop(Xref)</name>
<fsummary>Delete an Xref server.</fsummary>
<type>
<v>Xref = xref()</v>
</type>
<desc>
<p>Stops an <seealso marker="#xref_server">Xref server</seealso>.</p>
</desc>
</func>
<func>
<name>update(Xref [, Options]) -> {ok, Modules} | Error</name>
<fsummary>Replace newly compiled analyzed modules.</fsummary>
<type>
<v>Error = {error, module(), Reason}</v>
<v>Modules = [module()]</v>
<v>Options = [Option] | Option</v>
<v>Option = {verbose, bool()} | {warnings, bool()}</v>
<v>Reason = {invalid_options, term()} | {module_mismatch, module(), ReadModule} | - see also add_module -</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Replaces the <seealso marker="#module_data">module data</seealso> of all <seealso marker="#analyzed_module">analyzed modules</seealso> the BEAM
files of which have been modified since last read by an
<c>add</c> function or <c>update</c>. Application membership
of the modules is retained, and so is the value of the
<c>builtins</c> option. Returns a sorted list
of the names of the replaced modules.</p>
</desc>
</func>
<func>
<name>variables(Xref [, Options]) -> {ok, [VariableInfo]}</name>
<fsummary>Return the names of variables.</fsummary>
<type>
<v>Options = [Option] | Option</v>
<v>Option = predefined | user | {verbose, bool()}</v>
<v>Reason = {invalid_options, term()}</v>
<v>VariableInfo = {predefined, [variable()]} | {user, [variable()]}</v>
<v>Xref = xref()</v>
</type>
<desc>
<p>Returns a sorted lists of the names of the variables of an
<seealso marker="#xref_server">Xref server</seealso>.
The default is to return the <seealso marker="#user_variable">user variables</seealso> only.</p>
</desc>
</func>
</funcs>
<section>
<title>See Also</title>
<p>beam_lib(3), digraph(3), digraph_utils(3), regexp(3),
<seealso marker="xref_chapter">TOOLS User's Guide</seealso></p>
</section>
</erlref>
