From d3ece60d52880fb273da3c4aa07655a0eeddeafb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Wed, 16 May 2012 10:49:36 +0200
Subject: Introduce a representation for maps in Core Erlang

---
 lib/compiler/src/core_parse.hrl |  6 ++++++
 lib/compiler/src/core_parse.yrl | 30 +++++++++++++++++++++++++++++-
 lib/compiler/src/core_pp.erl    | 16 ++++++++++++++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/lib/compiler/src/core_parse.hrl b/lib/compiler/src/core_parse.hrl
index 0b8f4d8895..c134747991 100644
--- a/lib/compiler/src/core_parse.hrl
+++ b/lib/compiler/src/core_parse.hrl
@@ -96,3 +96,9 @@
 -record(c_values, {anno=[], es}).	% es :: [Tree]
 
 -record(c_var, {anno=[], name :: cerl:var_name()}).
+
+-record(c_map_pair, {anno=[], key, val}).
+
+-record(c_map, {anno=[],
+		var=#c_literal{val=[]} :: #c_var{} | #c_literal{},
+		es :: [#c_map_pair{}]}).
diff --git a/lib/compiler/src/core_parse.yrl b/lib/compiler/src/core_parse.yrl
index 4e98a8c2da..b072950eeb 100644
--- a/lib/compiler/src/core_parse.yrl
+++ b/lib/compiler/src/core_parse.yrl
@@ -21,6 +21,8 @@
 %% Have explicit productions for annotated phrases named anno_XXX.
 %% This just does an XXX and adds the annotation.
 
+Expect 1.
+
 Nonterminals
 
 module_definition module_export module_attribute module_defs
@@ -44,6 +46,9 @@ receive_expr timeout try_expr
 sequence catch_expr
 variable clause clause_pattern
 
+map_expr map_pairs map_pair
+map_pattern map_pair_patterns map_pair_pattern
+
 annotation anno_fun anno_expression anno_expressions
 anno_variable anno_variables anno_pattern anno_patterns
 anno_function_name
@@ -53,7 +58,7 @@ Terminals
 
 %% Separators
 
-'(' ')' '{' '}' '[' ']' '|' ',' '->' '=' '/' '<' '>' ':' '-|' '#'
+'(' ')' '{' '}' '[' ']' '|' ',' '->' '=' '/' '<' '>' ':' '-|' '#' '~'
 
 %% Keywords (atoms are assumed to always be single-quoted).
 
@@ -166,6 +171,7 @@ anno_patterns -> anno_pattern : ['$1'].
 
 other_pattern -> atomic_pattern : '$1'.
 other_pattern -> tuple_pattern : '$1'.
+other_pattern -> map_pattern : '$1'.
 other_pattern -> cons_pattern : '$1'.
 other_pattern -> binary_pattern : '$1'.
 other_pattern -> anno_variable '=' anno_pattern :
@@ -176,6 +182,16 @@ atomic_pattern -> atomic_literal : '$1'.
 tuple_pattern -> '{' '}' : c_tuple([]).
 tuple_pattern -> '{' anno_patterns '}' : c_tuple('$2').
 
+map_pattern -> '~' '{' '}' '~' : #c_map{es=[]}.
+map_pattern -> '~' '{' map_pair_patterns '}' '~' :
+		   #c_map{es=lists:sort('$3')}.
+
+map_pair_patterns -> map_pair_pattern : ['$1'].
+map_pair_patterns -> map_pair_pattern ',' map_pair_patterns : ['$1' | '$3'].
+
+map_pair_pattern -> '~' '<' anno_pattern ',' anno_pattern '>' :
+			#c_map_pair{key='$3',val='$5'}.
+
 cons_pattern -> '[' anno_pattern tail_pattern :
 		    #c_cons{hd='$2',tl='$3'}.
 
@@ -240,6 +256,7 @@ single_expression -> primop_expr : '$1'.
 single_expression -> try_expr : '$1'.
 single_expression -> sequence : '$1'.
 single_expression -> catch_expr : '$1'.
+single_expression -> map_expr : '$1'.
 
 literal -> atomic_literal : '$1'.
 literal -> tuple_literal : '$1'.
@@ -267,6 +284,17 @@ tail_literal -> ',' literal tail_literal : #c_cons{hd='$2',tl='$3'}.
 tuple -> '{' '}' : c_tuple([]).
 tuple -> '{' anno_expressions '}' : c_tuple('$2').
 
+map_expr -> '~' '{' '}' '~' : #c_map{es=[]}.
+map_expr -> '~' '{' map_pairs  '}' '~' : #c_map{es='$3'}.
+map_expr -> variable '~' '{' '}' '~' : #c_map{var='$',es=[]}.
+map_expr -> variable '~' '{' map_pairs  '}' '~' : #c_map{var='$1',es='$4'}.
+
+map_pairs -> map_pair : ['$1'].
+map_pairs -> map_pair ',' map_pairs : ['$1' | '$3'].
+
+map_pair -> '~' '<' anno_expression ',' anno_expression'>' :
+		#c_map_pair{key='$3',val='$5'}.
+
 cons -> '[' anno_expression tail : c_cons('$2', '$3').
 
 tail -> ']' : #c_literal{val=[]}.
diff --git a/lib/compiler/src/core_pp.erl b/lib/compiler/src/core_pp.erl
index 1f91a52be3..c8c59b9246 100644
--- a/lib/compiler/src/core_pp.erl
+++ b/lib/compiler/src/core_pp.erl
@@ -161,6 +161,22 @@ format_1(#c_tuple{es=Es}, Ctxt) ->
      format_hseq(Es, ",", add_indent(Ctxt, 1), fun format/2),
      $}
     ];
+format_1(#c_map{var=#c_var{}=Var,es=Es}, Ctxt) ->
+    [format_1(Var, Ctxt),
+     "~{",
+     format_hseq(Es, ",", add_indent(Ctxt, 1), fun format/2),
+     "}~"
+    ];
+format_1(#c_map{es=Es}, Ctxt) ->
+    ["~{",
+     format_hseq(Es, ",", add_indent(Ctxt, 1), fun format/2),
+     "}~"
+    ];
+format_1(#c_map_pair{key=K,val=V}, Ctxt) ->
+    ["~<",
+     format_hseq([K,V], ",", add_indent(Ctxt, 1), fun format/2),
+     ">"
+    ];
 format_1(#c_cons{hd=H,tl=T}, Ctxt) ->
     Txt = ["["|format(H, add_indent(Ctxt, 1))],
     [Txt|format_list_tail(T, add_indent(Ctxt, width(Txt, Ctxt)))];
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