Issue #43 - Customizable operation parse error

src/Interval.js

@@ -51,7 +51,7 @@ Interval.prototype = {
 
   getLineAndColumnMessage: function() {
     var range = [this.startIdx, this.endIdx];
-    return util.getLineAndColumnMessage(this.inputStream.source, this.startIdx, range);
+    return util.describeSourceLocation(this.inputStream.source, this.startIdx, true, range);
   },
 
   // Returns an array of 0, 1, or 2 intervals that represents the result of the

src/MatchResult.js

@@ -147,6 +147,28 @@ MatchFailure.prototype.getRightmostFailures = function() {
   return this._failures;
 };
 
+// optConfig has two options:
+// includeSource=true shows the problematic source code.
+// includeLineNumbers=true shows the problematic line numbers.
+MatchFailure.prototype.getMessage = function(optConfig) {
+  var config = optConfig || {};
+  var source = this.state.inputStream.source;
+  var detail = 'Expected ' + this.getExpectedText();
+
+  // use default values if not defined
+  var includeSource = config.includeSource == null ? true : config.includeSource;
+  var includeLineNumbers = config.includeLineNumbers == null ? true : config.includeLineNumbers;
+
+  if (!includeSource) {
+    return getShortMatchErrorMessage(
+        this.getRightmostFailurePosition(),
+        this.state.inputStream.source,
+        detail);
+  }
+  return util.describeSourceLocation(
+      source, this.getRightmostFailurePosition(), includeLineNumbers) + detail;
+};
+
 // Return a string summarizing the expected contents of the input stream when
 // the match failure occurred.
 MatchFailure.prototype.getExpectedText = function() {

src/Semantics.js

@@ -358,7 +358,7 @@ function parseSignature(signature, type) {
       signature,
       type === 'operation' ? 'OperationSignature' : 'AttributeSignature');
   if (r.failed()) {
-    throw new Error(r.message);
+    throw new Error(r.getMessage({includeSource: true, includeLineNumbers: false}));
   }
 
   return prototypeGrammarSemantics(r).parse();

src/util.js

@@ -93,7 +93,11 @@ exports.getLineAndColumn = function(str, offset) {
 
 // Return a nicely-formatted string describing the line and column for the
 // given offset in `str`.
-exports.getLineAndColumnMessage = function(str, offset /* ...ranges */) {
+
+exports.describeSourceLocation = function(str, offset, optIncludeLineNumbers /* ranges */) {
+
+  var includeLineNumbers = typeof optIncludeLineNumbers !== 'undefined' ?
+                            optIncludeLineNumbers : true;
   var repeatStr = common.repeatStr;
 
   var lineAndCol = exports.getLineAndColumn(str, offset);
@@ -109,7 +113,11 @@ exports.getLineAndColumnMessage = function(str, offset /* ...ranges */) {
 
   // Helper for appending formatting input lines to the buffer.
   function appendLine(num, content, prefix) {
-    sb.append(prefix + lineNumbers[num] + ' | ' + content + '\n');
+    if (includeLineNumbers) {
+      sb.append(prefix + lineNumbers[num] + ' | ' + content + '\n');
+    } else {
+      sb.append('  ' + content + '\n');
+    }
   }
 
   // Include the previous line for context if possible.
@@ -123,7 +131,7 @@ exports.getLineAndColumnMessage = function(str, offset /* ...ranges */) {
   // Start with a blank line, and indicate each range by overlaying a string of `~` chars.
   var lineLen = lineAndCol.line.length;
   var indicationLine = repeatStr(' ', lineLen + 1);
-  var ranges = Array.prototype.slice.call(arguments, 2);
+  var ranges = Array.prototype.slice.call(arguments, 3);
   for (var i = 0; i < ranges.length; ++i) {
     var startIdx = ranges[i][0];
     var endIdx = ranges[i][1];
@@ -135,7 +143,7 @@ exports.getLineAndColumnMessage = function(str, offset /* ...ranges */) {
 
     indicationLine = strcpy(indicationLine, repeatStr('~', endIdx - startIdx), startIdx);
   }
-  var gutterWidth = 2 + lineNumbers[1].length + 3;
+  var gutterWidth = includeLineNumbers ? 2 + lineNumbers[1].length + 3 : 2;
   sb.append(repeatStr(' ', gutterWidth));
   indicationLine = strcpy(indicationLine, '^', lineAndCol.colNum - 1);
   sb.append(indicationLine.replace(/ +$/, '') + '\n');
@@ -146,3 +154,9 @@ exports.getLineAndColumnMessage = function(str, offset /* ...ranges */) {
   }
   return sb.contents();
 };
+
+exports.getLineAndColumnMessage = function(str, offset) {
+  var args = Array.prototype.slice.call(arguments);
+  args.splice(2, 0, true);
+  return exports.describeSourceLocation.apply(this, args);
+};

test/test-errors.js

@@ -53,6 +53,22 @@ test('match failure', function(t) {
   t.end();
 });
 
+test('syntax error in added operation', function(t) {
+  var g = ohm.grammar('G { start = "a" "b" "c" "d" }');
+
+  try {
+    g.createSemantics().addOperation('myOperation(x, y', {});
+    t.fail('Expected an exception to be thrown');
+  } catch (e) {
+    t.equal(e.message, [
+      'Line 1, col 17:',
+      '  myOperation(x, y',
+      '                  ^',
+      'Expected ")"'].join('\n'));
+    }
+    t.end();
+});
+
 test('undeclared rules', function(t) {
   t.throws(
       function() { makeRuleWithBody('undeclaredRule'); },

test/test-util.js

@@ -13,6 +13,7 @@ var util = require('../src/util');
 // --------------------------------------------------------------------
 
 var getLineAndColumnMessage = util.getLineAndColumnMessage;
+var describeSourceLocation = util.describeSourceLocation;
 
 test('getLineAndColumnMessage', function(t) {
   t.equal(getLineAndColumnMessage('', 0), [
@@ -90,49 +91,49 @@ test('getLineAndColumnMessage', function(t) {
 });
 
 test('getLineAndColumnMessage with ranges', function(t) {
-  t.equal(getLineAndColumnMessage('3 + 4', 2, [0, 1]), [
+  t.equal(describeSourceLocation('3 + 4', 2, true, [0, 1]), [
     'Line 1, col 3:',
     '> 1 | 3 + 4',
     '      ~ ^',
     ''].join('\n'), 'a simple range');
 
-  t.equal(getLineAndColumnMessage('3 + 4', 2, [0, 1], [4, 5]), [
+  t.equal(describeSourceLocation('3 + 4', 2, true, [0, 1], [4, 5]), [
     'Line 1, col 3:',
     '> 1 | 3 + 4',
     '      ~ ^ ~',
     ''].join('\n'), 'more than one range');
 
-  t.equal(getLineAndColumnMessage('3 + 4', 2, [0, 100]), [
+  t.equal(describeSourceLocation('3 + 4', 2, true, [0, 100]), [
     'Line 1, col 3:',
     '> 1 | 3 + 4',
     '      ~~^~~',
     ''].join('\n'), 'end index out of bounds');
 
-  t.equal(getLineAndColumnMessage('3 + 4', 2, [0, 0]),
+  t.equal(describeSourceLocation('3 + 4', 2, true, [0, 0]),
           getLineAndColumnMessage('3 + 4', 2),
           'empty range');
 
-  t.equal(getLineAndColumnMessage('3 + 4', 0, [0, 3], [1, 5]), [
+  t.equal(describeSourceLocation('3 + 4', 0, true, [0, 3], [1, 5]), [
     'Line 1, col 1:',
     '> 1 | 3 + 4',
     '      ^~~~~',
     ''].join('\n'), 'overlapping ranges');
 
-  t.equal(getLineAndColumnMessage('blah\n3 + 4', 7, [5, 6]), [
+  t.equal(describeSourceLocation('blah\n3 + 4', 7, true, [5, 6]), [
     'Line 2, col 3:',
     '  1 | blah',
     '> 2 | 3 + 4',
     '      ~ ^',
     ''].join('\n'), 'range on second line');
 
-  t.equal(getLineAndColumnMessage('blah\n3 + 4', 7, [0, 6]), [
+  t.equal(describeSourceLocation('blah\n3 + 4', 7, true, [0, 6]), [
     'Line 2, col 3:',
     '  1 | blah',
     '> 2 | 3 + 4',
     '      ~ ^',
     ''].join('\n'), 'range crossing lines');
 
-  t.equal(getLineAndColumnMessage('blah\n3 + 4', 7, [0, 50]), [
+  t.equal(describeSourceLocation('blah\n3 + 4', 7, true, [0, 50]), [
     'Line 2, col 3:',
     '  1 | blah',
     '> 2 | 3 + 4',