1 # This file is part of NIT ( http://www.nitlanguage.org ).
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at
7 # http://www.apache.org/licenses/LICENSE-2.0
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
15 # Thansformations that simplify the AST of expressions
16 # This module transform complex AST `AExpr` nodes into simplier ones
22 intrude import semantize
::scope
23 intrude import semantize
::typing
25 redef class ToolContext
26 var transform_phase
: Phase = new TransformPhase(self, [typing_phase
, auto_super_init_phase
])
29 var opt_no_shortcut_range
: OptionBool = new OptionBool("Always instantiate a range and its iterator on 'for' loops", "--no-shortcut-range")
34 self.option_context
.add_option
(self.opt_no_shortcut_range
)
38 private class TransformPhase
41 redef fun process_npropdef
(npropdef
: APropdef)
45 var m
= npropdef
.mpropdef
46 if m
== null then return
47 var v
= new TransformVisitor(self, m
)
48 v
.enter_visit
(npropdef
)
50 val
= new ASTValidationVisitor
51 val
.enter_visit
(npropdef
)
55 private class TransformVisitor
58 var phase
: TransformPhase
59 var mmodule
: MModule is noinit
60 var mclassdef
: MClassDef is noinit
61 var mpropdef
: MPropDef
62 var builder
: ASTBuilder is noinit
66 self.mclassdef
= mpropdef
.mclassdef
67 self.mmodule
= mclassdef
.mmodule
68 self.builder
= new ASTBuilder(mmodule
, mpropdef
.mclassdef
.bound_mtype
)
73 if node
isa AAnnotations then return
74 node
.full_transform_visitor
(self)
77 # Get a primitive method or display a fatal error on `location`.
78 fun get_method
(location
: AExpr, name
: String, recv
: MClass): MMethod
80 return phase
.toolcontext
.modelbuilder
.force_get_primitive_method
(location
, name
, recv
, mmodule
)
85 private fun full_transform_visitor
(v
: TransformVisitor)
88 accept_transform_visitor
(v
)
90 private fun accept_transform_visitor
(v
: TransformVisitor)
96 redef fun full_transform_visitor
(v
: TransformVisitor)
98 var na
= comprehension
100 # We are building a comprehension array `array`
101 # Replace `self` with `array.push(self)`
102 var place
= detach_with_placeholder
103 var recv
= na
.nnew
.make_var_read
104 var nadd
= v
.builder
.make_call
(recv
, na
.push_callsite
.as(not null), [self])
105 place
.replace_with
(nadd
)
110 if is_broken
then return # Skip broken
112 accept_transform_visitor
(v
)
115 redef fun replace_with
(other
)
118 if other
isa AExpr then
119 if other
.implicit_cast_to
== null then other
.implicit_cast_to
= implicit_cast_to
124 redef class AVardeclExpr
125 # `var x = y` is replaced with `x = y`
127 # Declarations are only useful for scope rules
128 # Once names are associated with real objects, ther declaration become useless
129 # Therefore, if there is no initial value, then just ignore it
130 # Else, replace it with a simple assignment
131 redef fun accept_transform_visitor
(v
)
134 if nexpr
== null then
136 # note: not detached because the collection is currently under iteration
138 var nvar
= v
.builder
.make_var_assign
(self.variable
.as(not null), nexpr
)
144 redef class AIfexprExpr
145 # is replaced with `AIfExpr`
146 # Expression if and statement-if use two distinct classes for historical reasons
147 # However, on can replace the `AIfexprExpr` with the simpler `AIfExpr`
148 redef fun accept_transform_visitor
(v
)
150 var nif
= v
.builder
.make_if
(n_expr
, self.mtype
)
151 nif
.n_then
.add
(n_then
)
152 nif
.n_else
.add
(n_else
)
159 # `x or y` is replaced with `if x then x else y`
160 redef fun accept_transform_visitor
(v
)
162 var nif
= v
.builder
.make_if
(n_expr
, self.mtype
)
163 nif
.n_then
.add
(n_expr
.make_var_read
)
164 nif
.n_else
.add
(n_expr2
)
170 redef class AImpliesExpr
171 redef fun accept_transform_visitor
(v
)
178 # `x and y` is replaced with `if x then y else x`
179 redef fun accept_transform_visitor
(v
)
181 var nif
= v
.builder
.make_if
(n_expr
, self.mtype
)
182 nif
.n_then
.add
(n_expr2
)
183 nif
.n_else
.add
(n_expr
.make_var_read
)
189 redef class AWhileExpr
190 redef fun accept_transform_visitor
(v
)
192 var nloop
= v
.builder
.make_loop
193 var nif
= v
.builder
.make_if
(n_expr
, null)
197 if nblock
!= null then nif
.n_then
.add nblock
199 var escapemark
= self.break_mark
.as(not null)
200 var nbreak
= v
.builder
.make_break
(escapemark
)
201 nif
.n_else
.add nbreak
203 nloop
.break_mark
= self.break_mark
204 nloop
.continue_mark
= self.continue_mark
211 redef fun accept_transform_visitor
(v
)
213 var escapemark
= self.break_mark
214 assert escapemark
!= null
216 # Main block that will contain the whole for and will replace `self`
217 var nblock
= v
.builder
.make_block
219 # Part before the loop
220 var before
= v
.builder
.make_block
224 var nloop
= v
.builder
.make_loop
225 nloop
.break_mark
= escapemark
228 # Part before the body inside the loop
229 var begin
= v
.builder
.make_block
232 # The `do` block with then user code
233 var ndo
= v
.builder
.make_do
234 ndo
.break_mark
= escapemark
.continue_mark
237 ndo
.add
self.n_block
.as(not null)
241 g
.transform_in
(v
, before
, begin
, nloop
, nblock
, escapemark
)
248 redef class AForGroup
249 private fun transform_in
(v
: TransformVisitor, before
, begin
, next
, finish
: AExpr, escapemark
: EscapeMark)
253 # Shortcut on explicit range
254 # Avoid the instantiation of the range and the iterator
255 if self.variables
.length
== 1 and nexpr
isa ARangeExpr and not v
.phase
.toolcontext
.opt_no_shortcut_range
.value
then
256 # Before: evaluate bounds
257 var variable
= variables
.first
258 before
.add v
.builder
.make_var_assign
(variable
, nexpr
.n_expr
)
259 var to
= nexpr
.n_expr2
262 # Begin: check variable
263 var is_ok
= v
.builder
.make_call
(v
.builder
.make_var_read
(variable
, variable
.declared_type
.as(not null)), method_lt
.as(not null), [to
.make_var_read
])
264 var nif
= v
.builder
.make_if
(is_ok
, null)
266 nif
.n_else
.add v
.builder
.make_break
(escapemark
)
268 # Next: increment one
269 var one
= v
.builder
.make_int
(1)
270 var succ
= v
.builder
.make_call
(v
.builder
.make_var_read
(variable
, variable
.declared_type
.as(not null)), method_successor
.as(not null), [one
])
271 next
.add v
.builder
.make_var_assign
(variable
, succ
)
275 # Before: evaluate expr, make the iterator
277 var iter
= v
.builder
.make_call
(nexpr
.make_var_read
, method_iterator
.as(not null), null)
280 # Begin: check iterator `is_ok`
281 var is_ok
= v
.builder
.make_call
(iter
.make_var_read
, method_is_ok
.as(not null), null)
282 var nif
= v
.builder
.make_if
(is_ok
, null)
284 nif
.n_else
.add v
.builder
.make_break
(escapemark
)
286 # Begin: assign automatic variables
287 if variables
.length
== 1 then
288 var item
= v
.builder
.make_call
(iter
.make_var_read
, method_item
.as(not null), null)
289 begin
.add v
.builder
.make_var_assign
(variables
.first
, item
)
290 else if variables
.length
== 2 then
291 var key
= v
.builder
.make_call
(iter
.make_var_read
, method_key
.as(not null), null)
292 begin
.add v
.builder
.make_var_assign
(variables
[0], key
)
293 var item
= v
.builder
.make_call
(iter
.make_var_read
, method_item
.as(not null), null)
294 begin
.add v
.builder
.make_var_assign
(variables
[1], item
)
300 next
.add v
.builder
.make_call
(iter
.make_var_read
, method_next
.as(not null), null)
302 # Finish: call finish
303 var method_finish
= method_finish
304 if method_finish
!= null then
305 finish
.add v
.builder
.make_call
(iter
.make_var_read
, method_finish
, null)
310 redef class AWithExpr
311 # is replaced with a do/end and injected calls to `start` and `finish`
313 # Basically, the following
321 # is transformed into
332 # The point is that `finish` is called even if the block is escaped.
333 redef fun accept_transform_visitor
(v
)
335 var escapemark
= self.break_mark
336 assert escapemark
!= null
338 var nblock
= v
.builder
.make_block
344 var ndo
= v
.builder
.make_do
345 ndo
.break_mark
= escapemark
347 var start
= v
.builder
.make_call
(nexpr
.make_var_read
, method_start
.as(not null), null)
351 ndo
.add
self.n_block
.as(not null)
355 nblock
.add v
.builder
.make_call
(nexpr
.make_var_read
, method_finish
.as(not null), null)
361 redef class AArrayExpr
362 # `[x,y]` is replaced with
365 # var t = new Array[X].with_capacity(2)
370 redef fun full_transform_visitor
(v
)
372 if is_broken
then return # Skip broken
374 var nblock
= v
.builder
.make_block
376 var nnew
= v
.builder
.make_new
(with_capacity_callsite
.as(not null), [v
.builder
.make_int
(n_exprs
.length
)])
383 for nexpr
in self.n_exprs
do
386 var nres
= nnew
.make_var_read
392 private var nnew
: ANewExpr is noinit
395 redef class ACrangeExpr
396 # `[x..y]` is replaced with `new Range[X](x,y)`
397 redef fun accept_transform_visitor
(v
)
399 if parent
isa AForGroup then return # to permit shortcut ranges
400 replace_with
(v
.builder
.make_new
(init_callsite
.as(not null), [n_expr
, n_expr2
]))
404 redef class AOrangeExpr
405 # `[x..y[` is replaced with `new Range[X].without_last(x,y)`
406 redef fun accept_transform_visitor
(v
)
408 if parent
isa AForGroup then return # to permit shortcut ranges
409 replace_with
(v
.builder
.make_new
(init_callsite
.as(not null), [n_expr
, n_expr2
]))
414 # `(x)` is replaced with `x`
415 redef fun accept_transform_visitor
(v
)
421 redef class ASendReassignFormExpr
422 # `x.foo(y)+=z` is replaced with
425 # x.foo(y) = x.foo(y) + z
428 # witch is, in reality:
431 # x."foo="(y, x.foo(y)."+"(z))
433 redef fun accept_transform_visitor
(v
)
435 var nblock
= v
.builder
.make_block
438 var read_args
= new Array[AExpr]
439 var write_args
= new Array[AExpr]
440 for a
in raw_arguments
do
442 read_args
.add
(a
.make_var_read
)
443 write_args
.add
(a
.make_var_read
)
446 var nread
= v
.builder
.make_call
(n_expr
.make_var_read
, callsite
.as(not null), read_args
)
448 var nnewvalue
= v
.builder
.make_call
(nread
, reassign_callsite
.as(not null), [n_value
])
450 write_args
.add
(nnewvalue
)
451 var nwrite
= v
.builder
.make_call
(n_expr
.make_var_read
, write_callsite
.as(not null), write_args
)
458 redef class AVarReassignExpr
459 # `v += z` is replaced with `v = v + z`
460 redef fun accept_transform_visitor
(v
)
462 var variable
= self.variable
.as(not null)
464 var nread
= v
.builder
.make_var_read
(variable
, read_type
.as(not null))
466 var nnewvalue
= v
.builder
.make_call
(nread
, reassign_callsite
.as(not null), [n_value
])
467 var nwrite
= v
.builder
.make_var_assign
(variable
, nnewvalue
)
473 redef class AAttrReassignExpr
474 # `x.a += z` is replaced with `x.a = x.a + z`
475 redef fun accept_transform_visitor
(v
)
477 var nblock
= v
.builder
.make_block
479 var attribute
= self.mproperty
.as(not null)
481 var nread
= v
.builder
.make_attr_read
(n_expr
.make_var_read
, attribute
)
482 var nnewvalue
= v
.builder
.make_call
(nread
, reassign_callsite
.as(not null), [n_value
])
483 var nwrite
= v
.builder
.make_attr_assign
(n_expr
.make_var_read
, attribute
, nnewvalue
)