Report consistent errors on look ahead + cached results

This should resolve issue #452, and is based entirely on a fix @nikku did on a local branch of PEG.js v0.10.0 (Currently at https://github.com/nikku/pegjs/tree/452-peg-js-0.10-fix). Also his test case from #555 is included. Fixes #452, Closes #555
pegjs · Jan 18, 2018 · f5b323b · Mingun · Jan 18, 2018 · nikku
1 parent 9b90fa1
commit f5b323b
Show file tree

Hide file tree

Showing 3 changed files with 235 additions and 39 deletions.
diff --git a/lib/compiler/passes/generate-js.js b/lib/compiler/passes/generate-js.js
@@ -143,7 +143,11 @@ function generateJS( ast, options ) {
 
         const parts = [];
 
-        parts.push( "" );
+        parts.push( [
+            "",
+            "var rule$expects = peg$expect;",
+            ""
+        ].join( "\n" ) );
 
         if ( options.trace ) {
 
@@ -163,9 +167,20 @@ function generateJS( ast, options ) {
             parts.push( [
                 "var key = peg$currPos * " + ast.rules.length + " + " + ruleIndexCode + ";",
                 "var cached = peg$resultsCache[key];",
+                "var rule$expectations = [];",
+                "",
+                "rule$expects = function (expected) {",
+                "  if (peg$silentFails === 0) peg$expect(expected);",
+                "  rule$expectations.push(expected);",
+                "}",
                 "",
                 "if (cached) {",
                 "  peg$currPos = cached.nextPos;",
+                "",
+                "  rule$expectations = cached.expectations;",
+                "  if (peg$silentFails === 0) {",
+                "    rule$expectations.map(peg$expect);",
+                "  }",
                 ""
             ].join( "\n" ) );
 
@@ -211,7 +226,11 @@ function generateJS( ast, options ) {
 
             parts.push( [
                 "",
-                "peg$resultsCache[key] = { nextPos: peg$currPos, result: " + resultCode + " };"
+                "peg$resultsCache[key] = {",
+                "  nextPos: peg$currPos,",
+                "  result: " + resultCode + ",",
+                "  expectations: rule$expectations",
+                "};"
             ].join( "\n" ) );
 
         }
@@ -479,9 +498,7 @@ function generateJS( ast, options ) {
             "          break;",
             "",
             "        case " + op.EXPECT + ":",             // EXPECT e
-            "          if (peg$silentFails === 0) {",
-            "            peg$expect(peg$expectations[bc[ip + 1]]);",
-            "          }",
+            "          rule$expects(peg$expectations[bc[ip + 1]]);",
             "          ip += 2;",
             "          break;",
             "",
@@ -840,7 +857,7 @@ function generateJS( ast, options ) {
                         break;
 
                     case op.EXPECT:             // EXPECT e
-                        parts.push( "if (peg$silentFails === 0) { peg$expect(" + e( bc[ ip + 1 ] ) + "); }" );
+                        parts.push( "rule$expects(" + e( bc[ ip + 1 ] ) + ");" );
                         ip += 2;
                         break;