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merging in gfxmonk's major refactor to the way that returns are pushed down into the interior of expressions

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This commit is contained in:
Jeremy Ashkenas
2010-03-21 11:28:05 -04:00
parent ce7c0d176b
commit 80230414a2
12 changed files with 162 additions and 320 deletions
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144
src/nodes.coffee
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@@ -57,7 +57,7 @@ exports.BaseNode: class BaseNode
top: if @top_sensitive() then @options.top else del @options, 'top'
closure: @is_statement() and not @is_pure_statement() and not top and
not @options.as_statement and not (this instanceof CommentNode) and
not (@contains (n) -> n.is_pure_statement())
not @contains_pure_statement()
if closure then @compile_closure(@options) else @compile_node(@options)
# Statements converted into expressions via closure-wrapping share a scope
@@ -82,13 +82,11 @@ exports.BaseNode: class BaseNode
idt += TAB while num -= 1
idt
# construct a node that returns the current node's result
# note that this is overridden for smarter behaviour for
# many statement nodes (eg IfNode, ForNode)
# Construct a node that returns the current node's result.
# Note that this is overridden for smarter behavior for
# many statement nodes (eg IfNode, ForNode)...
make_return: ->
if @is_statement()
throw new Error("Can't convert statement ${this} into a return value!")
return new ReturnNode(this)
new ReturnNode this
# Does this node, or any of its children, contain a node of a certain kind?
# Recursively traverses down the *children* of the nodes, yielding to a block
@@ -100,6 +98,11 @@ exports.BaseNode: class BaseNode
return true if node.contains and node.contains block
false
# Convenience for the most common use of contains. Does the node contain
# a pure statement?
contains_pure_statement: ->
@is_pure_statement() or @contains (n) -> n.is_pure_statement()
# Perform an in-order traversal of the AST. Crosses scope boundaries.
traverse: (block) ->
for node in @children
@@ -150,36 +153,19 @@ exports.Expressions: class Expressions extends BaseNode
empty: ->
@expressions.length is 0
# make a copy of this node
# Make a copy of this node.
copy: ->
new Expressions(@children.slice())
new Expressions @children.slice()
# an Expressions node does not return its entire body, rather it
# ensures that the final expression is returned
# An Expressions node does not return its entire body, rather it
# ensures that the final expression is returned.
make_return: ->
last_expr_idx: -1
for i in [@expressions.length-1 .. 0]
if not (@expressions[i] instanceof CommentNode)
last_expr_idx: i
last_expr: @expressions[i]
break
if last_expr_idx < 0
# just add a return null to ensure return is always called
@push(new ReturnNode(literal(null)))
else
return this if (last_expr instanceof ReturnNode)
@push(new ReturnNode(literal(null))) if last_expr.is_statement()
# we still make an attempt at converting statements,
# since many are able to be returned in some fashion
try
converted = last_expr.make_return()
@expressions[last_expr_idx] = converted
catch e
# ignore
return this
idx: @expressions.length - 1
last: @expressions[idx]
last: @expressions[idx -= 1] if last instanceof CommentNode
return this if not last or last instanceof ReturnNode
@expressions[idx]: last.make_return() unless last.contains_pure_statement()
this
# An **Expressions** is the only node that can serve as the root.
compile: (o) ->
@@ -211,10 +197,8 @@ exports.Expressions: class Expressions extends BaseNode
# statement, ask the statement to do so.
compile_expression: (node, o) ->
@tab: o.indent
stmt: node.is_statement()
compiled_node = node.compile(merge(o, {top:true}))
return compiled_node if stmt
return "${@idt()}${compiled_node};"
compiled_node: node.compile merge o, {top: true}
if node.is_statement() then compiled_node else "${@idt()}$compiled_node;"
# Wrap up the given nodes as an **Expressions**, unless it already happens
# to be one.
@@ -260,18 +244,8 @@ exports.ReturnNode: class ReturnNode extends BaseNode
@children: [@expression: expression]
compile_node: (o) ->
if @expression.is_statement()
return @compile_statement(o)
else
compiled_expr: @expression.compile(o)
return "${@tab}return ${compiled_expr};"
compile_statement: (o) ->
# split statement into computation and return, via a temporary variable
temp_var: literal(o.scope.free_variable())
assign: new AssignNode(temp_var, @expression)
ret: new ReturnNode(temp_var)
[assign.compile(merge(o, {as_statement:true})), ret.compile(o)].join("\n")
o.as_statement: true if @expression.is_statement()
"${@tab}return ${@expression.compile(o)};"
statement ReturnNode, true
@@ -309,10 +283,7 @@ exports.ValueNode: class ValueNode extends BaseNode
@has_properties() and @properties[@properties.length - 1] instanceof SliceNode
make_return: ->
if not @has_properties()
return @base.make_return()
else
return super()
if @has_properties() then super() else @base.make_return()
# The value can be unwrapped as its inner node, if there are no attached
# properties.
@@ -364,6 +335,9 @@ exports.CommentNode: class CommentNode extends BaseNode
@lines: lines
this
make_return: ->
this
compile_node: (o) ->
"$@tab//" + @lines.join("\n$@tab//")
@@ -377,9 +351,11 @@ exports.CallNode: class CallNode extends BaseNode
type: 'Call'
constructor: (variable, args) ->
@children: flatten [@variable: variable, @args: (args or [])]
@is_new: false
@is_super: variable is 'super'
@variable: if @is_super then null else variable
@children: compact flatten [@variable, @args: (args or [])]
@compile_splat_arguments: SplatNode.compile_mixed_array <- @, @args
@is_new: false
# Tag this invocation as creating a new instance.
new_instance: ->
@@ -394,7 +370,7 @@ exports.CallNode: class CallNode extends BaseNode
for arg in @args
return @compile_splat(o) if arg instanceof SplatNode
args: (arg.compile(o) for arg in @args).join(', ')
return @compile_super(args, o) if @variable is 'super'
return @compile_super(args, o) if @is_super
"${@prefix()}${@variable.compile(o)}($args)"
# `super()` is converted into a call against the superclass's implementation
@@ -629,10 +605,10 @@ exports.ClassNode: class ClassNode extends BaseNode
# list of prototype property assignments.
constructor: (variable, parent, props) ->
@children: compact flatten [@variable: variable, @parent: parent, @properties: props or []]
@do_return: false
@returns: false
make_return: ->
@do_return: true
@returns: true
this
# Instead of generating the JavaScript string directly, we build up the
@@ -664,14 +640,10 @@ exports.ClassNode: class ClassNode extends BaseNode
else
constructor: new AssignNode(@variable, new CodeNode())
if @do_return
returns: new ReturnNode(@variable).compile(o)
else
returns: ''
construct: @idt() + constructor.compile(o) + ';\n'
props: if props.empty() then '' else props.compile(o) + '\n'
extension: if extension then @idt() + extension.compile(o) + ';\n' else ''
returns: if @returns then new ReturnNode(@variable).compile(o) else ''
"$construct$extension$props$returns"
statement ClassNode
@@ -698,7 +670,7 @@ exports.AssignNode: class AssignNode extends BaseNode
@variable instanceof ValueNode
make_return: ->
return new Expressions([this, new ReturnNode(@variable)])
return new Expressions [this, new ReturnNode(@variable)]
is_statement: ->
@is_value() and (@variable.is_array() or @variable.is_object())
@@ -724,8 +696,7 @@ exports.AssignNode: class AssignNode extends BaseNode
o.scope.find name unless @is_value() and @variable.has_properties()
val: "$name = $val"
return "$@tab$val;" if stmt
val: "($val)" if not top
return val
if top then val else "($val)"
# Brief implementation of recursive pattern matching, when assigning array or
# object literals to a value. Peeks at their properties to assign inner names.
@@ -899,7 +870,7 @@ exports.WhileNode: class WhileNode extends BaseNode
this
make_return: ->
@do_return: true
@returns: true
this
top_sensitive: ->
@@ -909,7 +880,7 @@ exports.WhileNode: class WhileNode extends BaseNode
# *while* can be used as a part of a larger expression -- while loops may
# return an array containing the computed result of each iteration.
compile_node: (o) ->
top: del(o, 'top') and not @do_return
top: del(o, 'top') and not @returns
o.indent: @idt(1)
o.top: true
cond: @condition.compile(o)
@@ -921,7 +892,7 @@ exports.WhileNode: class WhileNode extends BaseNode
pre: "$set${@tab}while ($cond)"
return "$pre null;$post" if not @body
@body: Expressions.wrap([new IfNode(@filter, @body)]) if @filter
if @do_return
if @returns
post: new ReturnNode(literal(rvar)).compile(merge(o, {indent: @idt()}))
else
post: ''
@@ -1049,8 +1020,8 @@ exports.ThrowNode: class ThrowNode extends BaseNode
constructor: (expression) ->
@children: [@expression: expression]
# A **ThrowNode** is already a return, of sorts...
make_return: ->
# a throw is already a return...
return this
compile_node: (o) ->
@@ -1098,7 +1069,8 @@ exports.ParentheticalNode: class ParentheticalNode extends BaseNode
is_statement: ->
@expression.is_statement()
make_return: -> @expression.make_return()
make_return: ->
@expression.make_return()
compile_node: (o) ->
code: @expression.compile(o)
@@ -1129,27 +1101,25 @@ exports.ForNode: class ForNode extends BaseNode
@object: !!source.object
[@name, @index]: [@index, @name] if @object
@children: compact [@body, @source, @filter]
@do_return: false
@returns: false
top_sensitive: ->
true
make_return: ->
@do_return: true
@returns: true
this
compile_return_value: (retvar, o) ->
if @do_return
return new ReturnNode(literal(retvar)).compile(o)
else
return retvar or ''
compile_return_value: (val, o) ->
return new ReturnNode(literal(val)).compile(o) if @returns
val or ''
# Welcome to the hairiest method in all of CoffeeScript. Handles the inner
# loop, filtering, stepping, and result saving for array, object, and range
# comprehensions. Some of the generated code can be shared in common, and
# some cannot.
compile_node: (o) ->
top_level: del(o, 'top') and not @do_return
top_level: del(o, 'top') and not @returns
range: @source instanceof ValueNode and @source.base instanceof RangeNode and not @source.properties.length
source: if range then @source.base else @source
scope: o.scope
@@ -1207,7 +1177,7 @@ exports.IfNode: class IfNode extends BaseNode
@condition: condition
@body: body and body.unwrap()
@else_body: else_body and else_body.unwrap()
@children: compact [@condition, @body, @else_body]
@children: compact flatten [@condition, @body, @else_body]
@tags: tags or {}
@multiple: true if @condition instanceof Array
@condition: new OpNode('!', new ParentheticalNode(@condition)) if @tags.invert
@@ -1270,11 +1240,9 @@ exports.IfNode: class IfNode extends BaseNode
if @is_statement() then @compile_statement(o) else @compile_ternary(o)
make_return: ->
try
@body: @body.make_return() if @body
finally
@else_body: @else_body.make_return() if @else_body
return this
@body &&= @body.make_return()
@else_body &&= @else_body.make_return()
this
# Compile the **IfNode** as a regular *if-else* statement. Flattened chains
# force inner *else* bodies into statement form.
@@ -1315,7 +1283,7 @@ PushNode: exports.PushNode: {
wrap: (array, expressions) ->
expr: expressions.unwrap()
return expressions if expr.is_pure_statement() or expr.contains (n) -> n.is_pure_statement()
return expressions if expr.is_pure_statement() or expr.contains_pure_statement()
Expressions.wrap([new CallNode(
new ValueNode(literal(array), [new AccessorNode(literal('push'))]), [expr]
)])
@@ -1330,7 +1298,7 @@ ClosureNode: exports.ClosureNode: {
# Wrap the expressions body, unless it contains a pure statement,
# in which case, no dice.
wrap: (expressions, statement) ->
return expressions if expressions.contains (n) -> n.is_pure_statement()
return expressions if expressions.contains_pure_statement()
func: new ParentheticalNode(new CodeNode([], Expressions.wrap([expressions])))
call: new CallNode(new ValueNode(func, [new AccessorNode(literal('call'))]), [literal('this')])
if statement then Expressions.wrap([call]) else call