pegjs#30: add support for delimiter.

Mingun · Sep 22, 2013 · b809cd0 · b809cd0
1 parent e14add5
commit b809cd0
Show file tree

Hide file tree

Showing 2 changed files with 25 additions and 5 deletions.
diff --git a/README.md b/README.md
@@ -293,7 +293,7 @@ expression as many times as possible.
 Try to match the expression. If the match succeeds, return its match result,
 otherwise return an empty string.
 
-#### *expression* |count|<br> *expression* |min..max|
+#### *expression* |count|<br> *expression* |count,delimiter|<br> *expression* |min..max|<br> *expression* |min..max,delimiter|
 
 Match exact `count` repetitions of `expression`. If the match succeeds, return
 their match results in an array.
@@ -306,6 +306,10 @@ be omitted. If `min` omitted, then suppose to `0`. If `max` is omitted, then
 suppose to infinity. `expression |..|` equivalently `expression |0..|` and
 `expression *`. `expression |1..|` equivalently `expression +`.
 
+Optionally, you can specify delimiter as rule reference or arbitrary rule
+expression. Delimiter must appear between elements in parsed input. Results
+of delimiter expression will be dropped.
+
 `count`, `min` and `max` must be positive integers.
 
 #### & *expression*

diff --git a/lib/compiler/passes/generate-bytecode.js b/lib/compiler/passes/generate-bytecode.js
@@ -546,17 +546,33 @@ module.exports = function(ast, options) {
       var emptyArrayIndex = addConst('[]');
       var nullIndex       = addConst('null');
           // expressionCode put result on stack
-          expressionCode  = generate(node.expression, {
+      var expressionCode  = generate(node.expression, {
             sp:     context.sp + 1,
             env:    { },
             action: null
           });
-          /*minIndex        = generate(node.min, {
+      var expressionCode2 = node.delimiter ?
+          buildSequence(
+            generate(node.delimiter, {
+              sp:     context.sp + 1,
+              env:    { },
+              action: null
+            }),                         // item = delim();
+            buildCondition(
+              [op.IF_NOT_ERROR],        // if (item != null)
+              buildSequence(
+                op.POP,
+                expressionCode          //   item = expr()
+              ),
+              []
+            )
+          ) : expressionCode;
+      /*var minIndex        = generate(node.min, {
             sp:     context.sp + 1,
             env:    { },
             action: null
           });
-          maxIndex        = generate(node.max, {
+      var maxIndex        = generate(node.max, {
             sp:     context.sp + 1,
             env:    { },
             action: null
@@ -577,7 +593,7 @@ module.exports = function(ast, options) {
               [op.IF_ARRLEN_MAX],   //                          stack:[ [elem...] ]
               // push `null` - this break loop on next iteration.
               [op.PUSH, nullIndex], //     elem = null;         stack:[ [elem...], null ]
-              expressionCode        //   } else {
+              expressionCode2       //   } else {
             )                       //     elem = expr();       stack:[ [elem...], elem ]
           )                         //   }
         ),                          // }                        stack:[ [elem...], elem ]