PEG.js grammar: Improve code block handling

* Rename the |Action| rule to |CodeBlock| (it better describes what
    the rule matches).

  * Implement the rule in a simpler way and move it after more basic
    lexical elements.

spec/parser.spec.js

@@ -389,35 +389,6 @@ describe("PEG.js grammar parser", function() {
     expect('start =//aaa\n"abcd"').toParseAs(trivialGrammar);
   });
 
-  /* Canonical Action is "{ code }". */
-  it("parses Action", function() {
-    expect('start = "abcd" { code }').toParseAs(actionGrammar(" code "));
-
-    expect('start = "abcd" { code }\n').toParseAs(actionGrammar(" code "));
-  });
-
-  /* Canonical Braced is "{ code }". */
-  it("parses Braced", function() {
-    expect('start = "abcd" {}'         ).toParseAs(actionGrammar(""));
-    expect('start = "abcd" {{a}}'      ).toParseAs(actionGrammar("{a}"));
-    expect('start = "abcd" {abcd}'     ).toParseAs(actionGrammar("abcd"));
-    expect('start = "abcd" {{a}{b}{c}}').toParseAs(actionGrammar("{a}{b}{c}"));
-  });
-
-  /* Canonical NonBraceCharacters is "abcd". */
-  it("parses NonBraceCharacters", function() {
-    expect('start = "abcd" {a}'  ).toParseAs(actionGrammar("a"));
-    expect('start = "abcd" {abc}').toParseAs(actionGrammar("abc"));
-  });
-
-  /* Canonical NonBraceCharacter is "a". */
-  it("parses NonBraceCharacter", function() {
-    expect('start = "abcd" {a}').toParseAs(actionGrammar("a"));
-
-    expect('start = "abcd" {{}').toFailToParse();
-    expect('start = "abcd" {}}').toFailToParse();
-  });
-
   /* Canonical Identifier is "a". */
   it("parses Identifier", function() {
     expect('start = a:"abcd"').toParseAs(oneRuleGrammar(labeledAbcd));
@@ -590,6 +561,21 @@ describe("PEG.js grammar parser", function() {
 
   /* Digit rules are not tested. */
 
+  /* Canonical CodeBlock is "{ code }". */
+  it("parses CodeBlock", function() {
+    expect('start = "abcd" { code }').toParseAs(actionGrammar(" code "));
+  });
+
+  /* Canonical Code is "code". */
+  it("parses Code", function() {
+    expect('start = "abcd" {a}'  ).toParseAs(actionGrammar("a"));
+    expect('start = "abcd" {{a}}').toParseAs(actionGrammar("{a}"));
+    expect('start = "abcd" {aaa}').toParseAs(actionGrammar("aaa"));
+
+    expect('start = "abcd" {{}').toFailToParse();
+    expect('start = "abcd" {}}').toFailToParse();
+  });
+
   /* Unicode character category rules are not tested. */
 
   /* Token rules are not tested. */

src/parser.pegjs

@@ -41,7 +41,7 @@ Grammar
     }
 
 Initializer
-  = code:Action (__ ";")? {
+  = code:CodeBlock (__ ";")? {
       return {
         type: "initializer",
         code: code
@@ -77,7 +77,7 @@ Choice
     }
 
 Sequence
-  = first:Labeled rest:(__ Labeled)* __ code:Action {
+  = first:Labeled rest:(__ Labeled)* __ code:CodeBlock {
       var expression = rest.length > 0
         ? { type: "sequence", elements: buildList(first, rest, 1) }
         : first;
@@ -110,7 +110,7 @@ Prefixed
         expression: expression
       };
     }
-  / "&" __ code:Action {
+  / "&" __ code:CodeBlock {
       return {
         type: "semantic_and",
         code: code
@@ -122,7 +122,7 @@ Prefixed
         expression: expression
       };
     }
-  / "!" __ code:Action {
+  / "!" __ code:CodeBlock {
       return {
         type: "semantic_not",
         code: code
@@ -203,18 +203,6 @@ MultiLineComment
 SingleLineComment
   = "//" (!LineTerminator SourceCharacter)*
 
-Action "action"
-  = braced:Braced __ { return braced.substr(1, braced.length - 2); }
-
-Braced
-  = $("{" (Braced / NonBraceCharacters)* "}")
-
-NonBraceCharacters
-  = NonBraceCharacter+
-
-NonBraceCharacter
-  = [^{}]
-
 Identifier
   = !ReservedWord name:IdentifierName { return name; }
   / name:IdentifierName {
@@ -406,6 +394,12 @@ DecimalDigit
 HexDigit
   = [0-9a-f]i
 
+CodeBlock "code block"
+  = "{" code:Code "}" { return code; }
+
+Code
+  = $([^{}] / "{" Code "}")*
+
 /*
  * Unicode Character Categories
  *