Change how error messages are shown

Instead of throwing the syntax errors with their source file location and needing to then catch them and call a `prettyErrorMessage` function in order to get the formatted error message, now syntax errors know how to pretty-print themselves (their `toString` method gets overridden).

An intermediate `catch` & re-`throw` is needed at the level of `CoffeeScript.compile` and friends. But the benefit of this approach is that now libraries that use the `CoffeeScript` object directly don't need to bother catching the possible compilation errors and calling a special function in order to get the nice error messages; they can just print the error itself (or let it bubble up) and the error will know how to pretty-print itself.

lib/coffee-script/coffee-script.js

@@ -1,6 +1,6 @@
 // Generated by CoffeeScript 1.6.3
 (function() {
-  var Lexer, Module, SourceMap, child_process, compile, compileFile, ext, fileExtensions, findExtension, fork, formatSourcePosition, fs, getSourceMap, helpers, lexer, loadFile, parser, path, sourceMaps, vm, _i, _len,
+  var Lexer, Module, SourceMap, child_process, compile, compileFile, ext, fileExtensions, findExtension, fork, formatSourcePosition, fs, getSourceMap, helpers, lexer, loadFile, parser, path, sourceMaps, vm, withPrettyErrors, _i, _len,
     __hasProp = {}.hasOwnProperty,
     __indexOf = [].indexOf || function(item) { for (var i = 0, l = this.length; i < l; i++) { if (i in this && this[i] === item) return i; } return -1; };
 
@@ -26,11 +26,25 @@
 
   exports.helpers = helpers;
 
-  exports.compile = compile = function(code, options) {
+  withPrettyErrors = function(fn) {
-    var answer, currentColumn, currentLine, fragment, fragments, header, js, map, merge, newLines, _i, _len;
+    return function(code, options) {
+      var err;
       if (options == null) {
         options = {};
       }
+      try {
+        return fn.call(this, code, options);
+      } catch (_error) {
+        err = _error;
+        err.code || (err.code = code);
+        err.filename || (err.filename = options.filename);
+        throw err;
+      }
+    };
+  };
+
+  exports.compile = compile = withPrettyErrors(function(code, options) {
+    var answer, currentColumn, currentLine, fragment, fragments, header, js, map, merge, newLines, _i, _len;
     merge = helpers.merge;
     if (options.sourceMap) {
       map = new SourceMap;
@@ -73,19 +87,19 @@
     } else {
       return js;
     }
-  };
+  });
 
-  exports.tokens = function(code, options) {
+  exports.tokens = withPrettyErrors(function(code, options) {
     return lexer.tokenize(code, options);
-  };
+  });
 
-  exports.nodes = function(source, options) {
+  exports.nodes = withPrettyErrors(function(source, options) {
     if (typeof source === 'string') {
       return parser.parse(lexer.tokenize(source, options));
     } else {
       return parser.parse(source);
     }
-  };
+  });
 
   exports.run = function(code, options) {
     var answer, mainModule, _ref;
@@ -178,8 +192,8 @@
       });
     } catch (_error) {
       err = _error;
-      err.filename = filename;
+      err.filename || (err.filename = filename);
-      err.code = stripped;
+      err.code || (err.code = stripped);
       throw err;
     }
     return answer;

lib/coffee-script/command.js

@@ -150,7 +150,7 @@
   };
 
   compileScript = function(file, input, base) {
-    var compiled, err, message, o, options, t, task, useColors;
+    var compiled, err, message, o, options, t, task;
     if (base == null) {
       base = null;
     }
@@ -195,8 +195,7 @@
       if (CoffeeScript.listeners('failure').length) {
         return;
       }
-      useColors = process.stdout.isTTY && !process.env.NODE_DISABLE_COLORS;
+      message = err.stack || ("" + err);
-      message = helpers.prettyErrorMessage(err, file || '[stdin]', input, useColors);
       if (o.watch) {
         return printLine(message + '\x07');
       } else {

lib/coffee-script/helpers.js

@@ -1,6 +1,6 @@
 // Generated by CoffeeScript 1.6.3
 (function() {
-  var buildLocationData, extend, flatten, last, repeat, _ref;
+  var buildLocationData, extend, flatten, last, repeat, syntaxErrorToString, _ref;
 
   exports.starts = function(string, literal, start) {
     return literal === string.substr(start, literal.length);
@@ -188,38 +188,41 @@
 
   exports.throwSyntaxError = function(message, location) {
     var error;
-    if (location.last_line == null) {
-      location.last_line = location.first_line;
-    }
-    if (location.last_column == null) {
-      location.last_column = location.first_column;
-    }
     error = new SyntaxError(message);
     error.location = location;
+    error.toString = syntaxErrorToString;
+    delete error.stack;
     throw error;
   };
 
-  exports.prettyErrorMessage = function(error, filename, code, useColors) {
+  syntaxErrorToString = function() {
-    var codeLine, colorize, end, first_column, first_line, last_column, last_line, marker, message, start, _ref1;
+    var codeLine, colorize, colorsEnabled, end, filename, first_column, first_line, last_column, last_line, marker, start, _ref1, _ref2;
-    if (!error.location) {
+    if (!(this.code && this.location)) {
-      return error.stack || ("" + error);
+      return Error.prototype.toString.call(this);
     }
-    filename = error.filename || filename;
+    _ref1 = this.location, first_line = _ref1.first_line, first_column = _ref1.first_column, last_line = _ref1.last_line, last_column = _ref1.last_column;
-    code = error.code || code;
+    if (last_line == null) {
-    _ref1 = error.location, first_line = _ref1.first_line, first_column = _ref1.first_column, last_line = _ref1.last_line, last_column = _ref1.last_column;
+      last_line = first_line;
-    codeLine = code.split('\n')[first_line];
+    }
+    if (last_column == null) {
+      last_column = first_column;
+    }
+    filename = this.filename || '[stdin]';
+    codeLine = this.code.split('\n')[first_line];
     start = first_column;
     end = first_line === last_line ? last_column + 1 : codeLine.length;
     marker = repeat(' ', start) + repeat('^', end - start);
-    if (useColors) {
+    if (typeof process !== "undefined" && process !== null) {
+      colorsEnabled = process.stdout.isTTY && !process.env.NODE_DISABLE_COLORS;
+    }
+    if ((_ref2 = this.colorful) != null ? _ref2 : colorsEnabled) {
       colorize = function(str) {
         return "\x1B[1;31m" + str + "\x1B[0m";
       };
       codeLine = codeLine.slice(0, start) + colorize(codeLine.slice(start, end)) + codeLine.slice(end);
       marker = colorize(marker);
     }
-    message = "" + filename + ":" + (first_line + 1) + ":" + (first_column + 1) + ": error: " + error.message + "\n" + codeLine + "\n" + marker;
+    return "" + filename + ":" + (first_line + 1) + ":" + (first_column + 1) + ": error: " + this.message + "\n" + codeLine + "\n" + marker;
-    return message;
   };
 
 }).call(this);

lib/coffee-script/repl.js

@@ -1,6 +1,6 @@
 // Generated by CoffeeScript 1.6.3
 (function() {
-  var CoffeeScript, addHistory, addMultilineHandler, fs, merge, nodeREPL, path, prettyErrorMessage, replDefaults, vm, _ref;
+  var CoffeeScript, addHistory, addMultilineHandler, fs, merge, nodeREPL, path, replDefaults, vm;
 
   fs = require('fs');
 
@@ -12,17 +12,17 @@
 
   CoffeeScript = require('./coffee-script');
 
-  _ref = require('./helpers'), merge = _ref.merge, prettyErrorMessage = _ref.prettyErrorMessage;
+  merge = require('./helpers').merge;
 
   replDefaults = {
     prompt: 'coffee> ',
     historyFile: process.env.HOME ? path.join(process.env.HOME, '.coffee_history') : void 0,
     historyMaxInputSize: 10240,
     "eval": function(input, context, filename, cb) {
-      var Assign, Block, Literal, Value, ast, err, js, _ref1;
+      var Assign, Block, Literal, Value, ast, err, js, _ref;
       input = input.replace(/\uFF00/g, '\n');
       input = input.replace(/^\(([\s\S]*)\n\)$/m, '$1');
-      _ref1 = require('./nodes'), Block = _ref1.Block, Assign = _ref1.Assign, Value = _ref1.Value, Literal = _ref1.Literal;
+      _ref = require('./nodes'), Block = _ref.Block, Assign = _ref.Assign, Value = _ref.Value, Literal = _ref.Literal;
       try {
         ast = CoffeeScript.nodes(input);
         ast = new Block([new Assign(new Value(new Literal('_')), ast, '=')]);
@@ -33,7 +33,8 @@
         return cb(null, vm.runInContext(js, context, filename));
       } catch (_error) {
         err = _error;
-        return cb(prettyErrorMessage(err, filename, input, true));
+        err.code || (err.code = input);
+        return cb(err);
       }
     }
   };
@@ -132,13 +133,13 @@
 
   module.exports = {
     start: function(opts) {
-      var build, major, minor, repl, _ref1;
+      var build, major, minor, repl, _ref;
       if (opts == null) {
         opts = {};
       }
-      _ref1 = process.versions.node.split('.').map(function(n) {
+      _ref = process.versions.node.split('.').map(function(n) {
         return parseInt(n);
-      }), major = _ref1[0], minor = _ref1[1], build = _ref1[2];
+      }), major = _ref[0], minor = _ref[1], build = _ref[2];
       if (major === 0 && minor < 8) {
         console.warn("Node 0.8.0+ required for CoffeeScript REPL");
         process.exit(1);

src/coffee-script.coffee

@@ -20,6 +20,17 @@ fileExtensions = ['.coffee', '.litcoffee', '.coffee.md']
 # Expose helpers for testing.
 exports.helpers = helpers
 
+# Function wrapper to add source file information to SyntaxErrors thrown by the
+# lexer/parser/compiler.
+withPrettyErrors = (fn) ->
+  (code, options = {}) ->
+    try
+      fn.call @, code, options
+    catch err
+      err.code or= code
+      err.filename or= options.filename
+      throw err
+
 # Compile CoffeeScript code to JavaScript, using the Coffee/Jison compiler.
 #
 # If `options.sourceMap` is specified, then `options.filename` must also be specified.  All
@@ -29,7 +40,7 @@ exports.helpers = helpers
 # in which case this returns a `{js, v3SourceMap, sourceMap}`
 # object, where sourceMap is a sourcemap.coffee#SourceMap object, handy for doing programatic
 # lookups.
-exports.compile = compile = (code, options = {}) ->
+exports.compile = compile = withPrettyErrors (code, options) ->
   {merge} = helpers
 
   if options.sourceMap
@@ -70,13 +81,13 @@ exports.compile = compile = (code, options = {}) ->
     js
 
 # Tokenize a string of CoffeeScript code, and return the array of tokens.
-exports.tokens = (code, options) ->
+exports.tokens = withPrettyErrors (code, options) ->
   lexer.tokenize code, options
 
 # Parse a string of CoffeeScript code or an array of lexed tokens, and
 # return the AST. You can then compile it by calling `.compile()` on the root,
 # or traverse it by using `.traverseChildren()` with a callback.
-exports.nodes = (source, options) ->
+exports.nodes = withPrettyErrors (source, options) ->
   if typeof source is 'string'
     parser.parse lexer.tokenize source, options
   else
@@ -150,8 +161,8 @@ compileFile = (filename, sourceMap) ->
     # As the filename and code of a dynamically loaded file will be different
     # from the original file compiled with CoffeeScript.run, add that
     # information to error so it can be pretty-printed later.
-    err.filename = filename
+    err.filename or= filename
-    err.code = stripped
+    err.code or= stripped
     throw err
 
   answer

src/command.coffee

@@ -141,8 +141,7 @@ compileScript = (file, input, base=null) ->
   catch err
     CoffeeScript.emit 'failure', err, task
     return if CoffeeScript.listeners('failure').length
-    useColors = process.stdout.isTTY and not process.env.NODE_DISABLE_COLORS
+    message = err.stack or "#{err}"
-    message = helpers.prettyErrorMessage err, file or '[stdin]', input, useColors
     if o.watch
       printLine message + '\x07'
     else

src/helpers.coffee

@@ -134,44 +134,45 @@ exports.isCoffee = (file) -> /\.((lit)?coffee|coffee\.md)$/.test file
 # Determine if a filename represents a Literate CoffeeScript file.
 exports.isLiterate = (file) -> /\.(litcoffee|coffee\.md)$/.test file
 
-# Throws a SyntaxError with a source file location data attached to it in a
+# Throws a SyntaxError from a given location.
-# property called `location`.
+# The error's `toString` will return an error message following the "standard"
+# format <filename>:<line>:<col>: <message> plus the line with the error and a
+# marker showing where the error is.
 exports.throwSyntaxError = (message, location) ->
-  location.last_line ?= location.first_line
-  location.last_column ?= location.first_column
   error = new SyntaxError message
   error.location = location
+  error.toString = syntaxErrorToString
+
+  # Prevent compiler error from showing the compiler's stacktrace.
+  delete error.stack
+
   throw error
 
-# Creates a nice error message like, following the "standard" format
+syntaxErrorToString = ->
-# <filename>:<line>:<col>: <message> plus the line with the error and a marker
+  return Error::toString.call @ unless @code and @location
-# showing where the error is.
-exports.prettyErrorMessage = (error, filename, code, useColors) ->
-  return error.stack or "#{error}" unless error.location
 
-  # Prefer original source file information stored in the error if present.
+  {first_line, first_column, last_line, last_column} = @location
-  filename = error.filename or filename
+  last_line ?= first_line
-  code     = error.code or code
+  last_column ?= first_column
 
-  {first_line, first_column, last_line, last_column} = error.location
+  filename = @filename or '[stdin]'
-  codeLine = code.split('\n')[first_line]
+  codeLine = @code.split('\n')[first_line]
   start    = first_column
   # Show only the first line on multi-line errors.
   end      = if first_line is last_line then last_column + 1 else codeLine.length
   marker   = repeat(' ', start) + repeat('^', end - start)
 
-  if useColors
+  # Check to see if we're running on a color-enabled TTY.
+  if process?
+    colorsEnabled = process.stdout.isTTY and not process.env.NODE_DISABLE_COLORS
+
+  if @colorful ? colorsEnabled
     colorize = (str) -> "\x1B[1;31m#{str}\x1B[0m"
     codeLine = codeLine[...start] + colorize(codeLine[start...end]) + codeLine[end..]
     marker   = colorize marker
 
-  message = """
+  """
-    #{filename}:#{first_line + 1}:#{first_column + 1}: error: #{error.message}
+    #{filename}:#{first_line + 1}:#{first_column + 1}: error: #{@message}
     #{codeLine}
     #{marker}
   """
-
-  # Uncomment to add stacktrace.
-  #message += "\n#{error.stack}"
-
-  message

src/repl.coffee

@@ -3,7 +3,7 @@ path = require 'path'
 vm = require 'vm'
 nodeREPL = require 'repl'
 CoffeeScript = require './coffee-script'
-{merge, prettyErrorMessage} = require './helpers'
+{merge} = require './helpers'
 
 replDefaults =
   prompt: 'coffee> ',
@@ -29,7 +29,9 @@ replDefaults =
       js = ast.compile bare: yes, locals: Object.keys(context)
       cb null, vm.runInContext(js, context, filename)
     catch err
-      cb prettyErrorMessage(err, filename, input, yes)
+      # AST's `compile` does not add source code information to syntax errors.
+      err.code or= input
+      cb err
 
 addMultilineHandler = (repl) ->
   {rli, inputStream, outputStream} = repl

test/error_messages.coffee

@@ -4,12 +4,10 @@
 # Ensure that errors of different kinds (lexer, parser and compiler) are shown
 # in a consistent way.
 
-{prettyErrorMessage} = CoffeeScript.helpers
-
 assertErrorFormat = (code, expectedErrorFormat) ->
   throws (-> CoffeeScript.run code), (err) ->
-    message = prettyErrorMessage err, 'test.coffee', code
+    err.colorful = no
-    eq expectedErrorFormat, message
+    eq expectedErrorFormat, "#{err}"
     yes
 
 test "lexer errors formating", ->
@@ -18,7 +16,7 @@ test "lexer errors formating", ->
     insideOutObject = }{
   ''',
   '''
-    test.coffee:2:19: error: unmatched }
+    [stdin]:2:19: error: unmatched }
     insideOutObject = }{
                       ^
   '''
@@ -28,7 +26,7 @@ test "parser error formating", ->
     foo in bar or in baz
   ''',
   '''
-    test.coffee:1:15: error: unexpected RELATION
+    [stdin]:1:15: error: unexpected RELATION
     foo in bar or in baz
                   ^^
   '''
@@ -38,7 +36,7 @@ test "compiler error formatting", ->
     evil = (foo, eval, bar) ->
   ''',
   '''
-    test.coffee:1:14: error: parameter name "eval" is not allowed
+    [stdin]:1:14: error: parameter name "eval" is not allowed
     evil = (foo, eval, bar) ->
                  ^^^^
   '''