instance-bound methods preserve the original function length

jashkenas/coffeescript#2489

Author: michaelficarra

lib/coffee-script/compiler.js

@@ -1,4 +1,4 @@
-{any, concat, concatMap, difference, foldl1, map, nub, owns, union} = require './functional-helpers'
+{any, concat, concatMap, difference, divMod, foldl1, map, nub, owns, union} = require './functional-helpers'
 {beingDeclared, usedAsExpression, envEnrichments} = require './helpers'
 CS = require './nodes'
 JS = require './js-nodes'
@@ -361,12 +361,14 @@ class exports.Compiler
         block.body.unshift stmt new JS.AssignmentExpression '=', ctorRef, compile @ctor.expression
       block.body.unshift ctor
 
-      if @boundMembers? and @boundMembers.length > 0
+      if @boundMembers.length > 0
         instance = genSym 'instance'
-        for memberName in @boundMembers
+        for protoAssignOp in @boundMembers
+          memberName = protoAssignOp.assignee.data.toString()
+          ps = (genSym() for _ in protoAssignOp.expression.parameters)
           member = memberAccess new JS.ThisExpression, memberName
           protoMember = memberAccess (memberAccess name, 'prototype'), memberName
-          fn = new JS.FunctionExpression null, [], new JS.BlockStatement [
+          fn = new JS.FunctionExpression null, ps, new JS.BlockStatement [
             stmt new JS.CallExpression (memberAccess protoMember, 'apply'), [instance, new JS.Identifier 'arguments']
           ]
           ctor.body.body.unshift stmt new JS.AssignmentExpression '=', member, fn
@@ -651,7 +653,15 @@ class exports.Compiler
     generateSymbols = do ->
 
       generatedSymbols = {}
-      format = (pre, counter) -> "#{pre}$#{counter or ''}"
+      format = (pre, counter) ->
+        if pre
+          "#{pre}$#{counter or ''}"
+        else
+          if counter < 26
+            String.fromCharCode 0x61 + counter
+          else
+            [div, mod] = divMod counter, 26
+            (format pre, div - 1) + format pre, mod
 
       generateName = (node, {usedSymbols, nsCounters}) ->
         if owns generatedSymbols, node.uniqueId
@@ -696,5 +706,5 @@ class exports.Compiler
       jsAST = walk.call ast, (-> (rules[@className] ? defaultRule).apply this, arguments), [], [], options
       generateSymbols jsAST,
         declaredSymbols: []
-        usedSymbols: collectIdentifiers jsAST
+        usedSymbols: jsReserved[..]
         nsCounters: {}

lib/coffee-script/functional-helpers.js

@@ -36,3 +36,9 @@
 @flip = (fn) -> (b, a) -> fn.call this, a, b
 
 @owns = do (hop = {}.hasOwnProperty) -> (a, b) -> hop.call a, b
+
+@divMod = (a, b) ->
+  c = a % b
+  mod = if c < 0 then c + b else c
+  div = Math.floor a / b
+  [div, mod]

lib/coffee-script/nodes.js

@@ -511,14 +511,14 @@ class
       name = name ? name[1] : null;
       parent = parent ? parent[3] : null;
       var boundMembers = [];
-      var stmts = body.block.statements;
+      var stmts = body.block != null ? body.block.statements : [];
       for(var i = 0, l = stmts.length; i < l; ++i) {
         var m = stmts[i];
         if(m.instanceof(CS.Constructor)) {
           ctor = m;
           stmts.splice(i, 1); --i; --l;
         } else if(m.instanceof(CS.ClassProtoAssignOp) && m.expression.instanceof(CS.BoundFunction)) {
-          boundMembers.push(m.assignee.data.toString());
+          boundMembers.push(m);
         }
       }
       return new CS.Class(name, parent, ctor, body.block, boundMembers).r(raw).p(line, column);
@@ -613,7 +613,7 @@ switch
 
 
 functionLiteral
-  = params:("(" _ parameterList _ ")" _)? arrow:("->" / "=>") body:functionBody? {
+  = params:("(" _ parameterList? _ ")" _)? arrow:("->" / "=>") body:functionBody? {
       if(!body) body = {block: null, raw: ''};
       var raw =
         (params ? params[0] + params[1] + params[2].raw + params[3] + params[4] + params[5] : '') +
@@ -624,7 +624,7 @@ functionLiteral
         case '=>': constructor = CS.BoundFunction; break;
         default: throw new Error('parsed function arrow ("' + arrow + '") not associated with a constructor');
       }
-      params = params ? params[2].list : [];
+      params = params && params[2] ? params[2].list : [];
       return new constructor(params, body.block).r(raw).p(line, column);
     }
   functionBody

lib/coffee-script/parser.js

@@ -144,7 +144,7 @@ createNodes
     ArrayInitialiser: [['members']] # :: [ArrayInitialiserMembers] -> ArrayInitialiser
     ObjectInitialiser: [['members']] # :: [ObjectInitialiserMember] -> ObjectInitialiser
     ObjectInitialiserMember: [['key', 'expression']] # :: ObjectInitialiserKeys -> Exprs -> ObjectInitialiserMember
-    Class: [['nameAssignee', 'parent', 'ctor', 'block', 'boundMembers']] # :: Maybe Assignable -> Maybe Exprs -> Maybe Exprs -> Maybe Exprs -> [string] -> Class
+    Class: [['nameAssignee', 'parent', 'ctor', 'block', 'boundMembers']] # :: Maybe Assignable -> Maybe Exprs -> Maybe Exprs -> Maybe Exprs -> [ClassProtoAssignOp] -> Class
     Constructor: [['expression']] # :: Exprs -> Constructor
     Functions: [ ['parameters', 'block'],
       Function: null # :: [Parameters] -> Maybe Exprs -> Function
@@ -261,6 +261,7 @@ handleLists SwitchCase, ['conditions']
 Block.wrap = (s) -> new Block(if s? then [s] else []).r(s.raw).p(s.line, s.column)
 
 Class::initialise = ->
+  @boundMembers ?= []
   @name = new GenSym 'class'
   if @nameAssignee?
     # TODO: factor this out, as it's useful elsewhere: short object literal members, NFEs from assignee, etc.