Implement #1495, Method call chaining

src/rewriter.coffee

@@ -131,7 +131,7 @@ class exports.Rewriter
 
     @scanTokens (token, i, tokens) ->
       [tag]     = token
-      [prevTag] = if i > 0 then tokens[i - 1] else []
+      [prevTag] = prevToken = if i > 0 then tokens[i - 1] else []
       [nextTag] = if i < tokens.length - 1 then tokens[i + 1] else []
       stackTop  = -> stack[stack.length - 1]
       startIdx  = i
@@ -159,6 +159,10 @@ class exports.Rewriter
         tokens.splice i, 0, generate 'CALL_END', ')'
         i += 1
 
+      endAllImplicitCalls = ->
+        while inImplicitCall()
+          endImplicitCall()
+
       startImplicitObject = (j, startsLine = yes) ->
         idx = j ? i
         stack.push ['{', idx, sameLine: yes, startsLine: startsLine, ours: yes]
@@ -275,9 +279,19 @@ class exports.Rewriter
       #       c
       #     .h a
       #
-      if prevTag is 'OUTDENT' and inImplicitCall() and tag in ['.', '?.', '::', '?::']
-        endImplicitCall()
-        return forward(1)
+      # and also
+      #
+      #     f a
+      #     .g b
+      #     .h a
+      #
+      if inImplicitCall() and tag in CALL_CLOSERS
+        if prevTag is 'OUTDENT'
+          endImplicitCall()
+          return forward(1)
+        if prevToken.newLine
+          endAllImplicitCalls()
+          return forward(1)
 
       stackTop()[2].sameLine = no if inImplicitObject() and tag in LINEBREAKS
 
@@ -356,7 +370,8 @@ class exports.Rewriter
       token[1] isnt ';' and token[0] in SINGLE_CLOSERS and
       not (token[0] is 'TERMINATOR' and @tag(i + 1) in EXPRESSION_CLOSE) and
       not (token[0] is 'ELSE' and starter isnt 'THEN') and
-      not (token[0] in ['CATCH', 'FINALLY'] and starter in ['->', '=>'])
+      not (token[0] in ['CATCH', 'FINALLY'] and starter in ['->', '=>']) or
+      token[0] in CALL_CLOSERS and @tokens[i - 1].newLine
 
     action = (token, i) ->
       @tokens.splice (if @tag(i - 1) is ',' then i - 1 else i), 0, outdent
@@ -471,3 +486,6 @@ SINGLE_CLOSERS   = ['TERMINATOR', 'CATCH', 'FINALLY', 'ELSE', 'OUTDENT', 'LEADIN
 
 # Tokens that end a line.
 LINEBREAKS       = ['TERMINATOR', 'INDENT', 'OUTDENT']
+
+# Tokens that close open calls when they follow a newline.
+CALL_CLOSERS = ['.', '?.', '::', '?::']

test/formatting.coffee

@@ -44,17 +44,60 @@ test "chained accesses split on period/newline, backwards and forwards", ->
     .reverse()
     .reverse()
   arrayEq ['c','b','a'], result
-  arrayEq ['c','b','a'], str
+  arrayEq ['c','b','a'],
+    str
     .split('')
     .reverse()
     .reverse()
     .reverse()
-  arrayEq ['c','b','a'], str.
+  arrayEq ['c','b','a'],
+    str.
     split('')
     .reverse().
     reverse()
     .reverse()
 
+test "#1495, method call chaining", ->
+  str = 'abc'
+
+  result = str.split ''
+              .join ', '
+  eq 'a, b, c', result
+
+  result = str
+  .split ''
+  .join ', '
+  eq 'a, b, c', result
+
+  eq 'a, b, c', (str
+    .split ''
+    .join ', '
+  )
+
+  eq 'abc',
+    'aaabbbccc'.replace /(\w)\1\1/g, '$1$1'
+               .replace /([abc])\1/g, '$1'
+
+  # Nested calls
+  result = [1..3]
+    .slice Math.max 0, 1
+    .concat [3]
+  arrayEq result, [2, 3, 3]
+
+  # Single line function arguments.
+  result = [1..6]
+    .map (x) -> x * x
+    .filter (x) -> x % 2 is 0
+    .reverse()
+  arrayEq result, [36, 16, 4]
+
+  # The parens are forced
+  result = str.split(''.
+    split ''
+    .join ''
+  ).join ', '
+  eq 'a, b, c', result
+
 # Operators
 
 test "newline suppression for operators", ->
@@ -65,9 +108,11 @@ test "newline suppression for operators", ->
   eq 6, six
 
 test "`?.` and `::` should continue lines", ->
-  ok not Date
-  ::
-  ?.foo
+  ok not (
+    Date
+    ::
+    ?.foo
+  )
   #eq Object::toString, Date?.
   #prototype
   #::