+++ /dev/null
-# This file is part of NIT ( http://www.nitlanguage.org ).
-#
-# Copyright 2012 Jean Privat <jean@pryen.org>
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-# Identification and scping of local variables and labels.
-module scope
-
-import phase
-
-redef class ToolContext
- var scope_phase: Phase = new ScopePhase(self, null)
-end
-
-private class ScopePhase
- super Phase
- redef fun process_npropdef(npropdef) do npropdef.do_scope(toolcontext)
-end
-
-
-# A local variable (including parameters, automatic variables and self)
-class Variable
- # The name of the variable (as used in the program)
- var name: String
-
- # Alias of `name`
- redef fun to_s do return self.name
-end
-
-# Mark where break and continue will branch.
-# Marks are either associated with a label of with a for_loop structure
-class EscapeMark
- # The name of the label (unless the mark is an anonymous loop mark)
- var name: nullable String
-
- # Is the mark atached to a loop (loop, while, for)
- # Such a mark is a candidate to a labelless 'continue' or 'break'
- var for_loop: Bool
-
- # Each 'continue' attached to the mark
- var continues: Array[AContinueExpr] = new Array[AContinueExpr]
-
- # Each 'break' attached to the mark
- var breaks: Array[ABreakExpr] = new Array[ABreakExpr]
-end
-
-# Visit a npropdef and:
-# * Identify variables and labels
-# * Associate each break and continue to its escapemark
-# * Transform `ACallFormExpr` that access a variable into `AVarFormExpr`
-# FIXME: Should the class be private?
-private class ScopeVisitor
- super Visitor
-
- # The tool context used to display errors
- var toolcontext: ToolContext
-
- var selfvariable: Variable = new Variable("self")
-
- init(toolcontext: ToolContext)
- do
- self.toolcontext = toolcontext
- scopes.add(new Scope)
- end
-
- # All stacked scope. `scopes.first` is the current scope
- private var scopes: List[Scope] = new List[Scope]
-
- # Regiter a local variable.
- # Display an error on toolcontext if a variable with the same name is masked.
- fun register_variable(node: ANode, variable: Variable): Bool
- do
- var name = variable.name
- var found = search_variable(name)
- if found != null then
- self.error(node, "Error: A variable named `{name}' already exists")
- return false
- end
- scopes.first.variables[name] = variable
- return true
- end
-
- # Look for a variable named `name`.
- # Return null if no such a variable is found.
- fun search_variable(name: String): nullable Variable
- do
- for scope in scopes do
- var res = scope.get_variable(name)
- if res != null then
- return res
- end
- end
- return null
- end
-
- redef fun visit(n)
- do
- n.accept_scope_visitor(self)
- end
-
- # Enter in a statement block `node` as inside a new scope.
- # The block can be optionally attached to an `escapemark`.
- private fun enter_visit_block(node: nullable AExpr, escapemark: nullable EscapeMark)
- do
- if node == null then return
- var scope = new Scope
- scope.escapemark = escapemark
- scopes.unshift(scope)
- enter_visit(node)
- scopes.shift
- end
-
- # Look for a label `name`.
- # Return nulll if no such a label is found.
- private fun search_label(name: String): nullable EscapeMark
- do
- for scope in scopes do
- var res = scope.escapemark
- if res != null and res.name == name then
- return res
- end
- end
- return null
- end
-
- # Create a new escape mark (possibly with a label)
- # Display an error on toolcontext if a label with the same name is masked.
- private fun make_escape_mark(nlabel: nullable ALabel, for_loop: Bool): EscapeMark
- do
- var name: nullable String
- if nlabel != null then
- var nid = nlabel.n_id
- if nid == null then
- var res = search_label("")
- if res != null then
- self.error(nlabel, "Syntax error: anonymous label already defined.")
- end
- name = ""
- else
- name = nid.text
- var found = self.search_label(name)
- if found != null then
- self.error(nlabel, "Syntax error: label {name} already defined.")
- end
- end
- else
- name = null
- end
- var res = new EscapeMark(name, for_loop)
- return res
- end
-
- # Look for an escape mark optionally associated with a label.
- # If a label is given, the the escapemark of this label is returned.
- # If there is no label, the nearest escapemark that is `for loop` is returned.
- # If there is no valid escapemark, then an error is displayed ans null is returned.
- # Return nulll if no such a label is found.
- private fun get_escapemark(node: ANode, nlabel: nullable ALabel): nullable EscapeMark
- do
- if nlabel != null then
- var nid = nlabel.n_id
- if nid == null then
- var res = search_label("")
- if res == null then
- self.error(nlabel, "Syntax error: invalid anonymous label.")
- return null
- end
- return res
- end
- var name = nid.text
- var res = search_label(name)
- if res == null then
- self.error(nlabel, "Syntax error: invalid label {name}.")
- return null
- end
- return res
- else
- for scope in scopes do
- var res = scope.escapemark
- if res != null then
- return res
- end
- end
- self.error(node, "Syntax Error: 'break' statment outside block.")
- return null
- end
- end
-
- # Display an error
- private fun error(node: ANode, message: String)
- do
- self.toolcontext.error(node.hot_location, message)
- end
-end
-
-private class Scope
- var variables: HashMap[String, Variable] = new HashMap[String, Variable]
-
- var escapemark: nullable EscapeMark = null
-
- fun get_variable(name: String): nullable Variable
- do
- if self.variables.has_key(name) then
- return self.variables[name]
- else
- return null
- end
- end
-end
-
-redef class ANode
- private fun accept_scope_visitor(v: ScopeVisitor)
- do
- visit_all(v)
- end
-end
-
-redef class APropdef
- # Entry point of the scope analysis
- fun do_scope(toolcontext: ToolContext)
- do
- var v = new ScopeVisitor(toolcontext)
- v.enter_visit(self)
- end
-end
-
-redef class AParam
- # The variable associated with the parameter
- var variable: nullable Variable
- redef fun accept_scope_visitor(v)
- do
- super
- var nid = self.n_id
- var variable = new Variable(nid.text)
- v.register_variable(nid, variable)
- self.variable = variable
- end
-end
-
-redef class AVardeclExpr
- # The variable associated with the variable declaration
- var variable: nullable Variable
- redef fun accept_scope_visitor(v)
- do
- super
- var nid = self.n_id
- var variable = new Variable(nid.text)
- v.register_variable(nid, variable)
- self.variable = variable
- end
-end
-
-redef class ASelfExpr
- # The variable associated with the self reciever
- var variable: nullable Variable
- redef fun accept_scope_visitor(v)
- do
- super
- self.variable = v.selfvariable
- end
-end
-
-redef class AContinueExpr
- # The escape mark associated with the continue
- var escapemark: nullable EscapeMark
- redef fun accept_scope_visitor(v)
- do
- super
- var escapemark = v.get_escapemark(self, self.n_label)
- if escapemark == null then return # Skip error
- if not escapemark.for_loop then
- v.error(self, "Error: cannot 'continue', only 'break'.")
- end
- escapemark.continues.add(self)
- self.escapemark = escapemark
- end
-end
-
-redef class ABreakExpr
- # The escape mark associated with the break
- var escapemark: nullable EscapeMark
- redef fun accept_scope_visitor(v)
- do
- super
- var escapemark = v.get_escapemark(self, self.n_label)
- if escapemark == null then return # Skip error
- escapemark.breaks.add(self)
- self.escapemark = escapemark
- end
-end
-
-
-redef class ADoExpr
- # The escape mark associated with the 'do' block
- var escapemark: nullable EscapeMark
- redef fun accept_scope_visitor(v)
- do
- self.escapemark = v.make_escape_mark(n_label, false)
- v.enter_visit_block(n_block, self.escapemark)
- end
-end
-
-redef class AIfExpr
- redef fun accept_scope_visitor(v)
- do
- v.enter_visit(n_expr)
- v.enter_visit_block(n_then, null)
- v.enter_visit_block(n_else, null)
- end
-end
-
-redef class AWhileExpr
- # The escape mark associated with the 'while'
- var escapemark: nullable EscapeMark
- redef fun accept_scope_visitor(v)
- do
- var escapemark = v.make_escape_mark(n_label, true)
- self.escapemark = escapemark
- v.enter_visit(n_expr)
- v.enter_visit_block(n_block, escapemark)
- end
-end
-
-redef class ALoopExpr
- # The escape mark associated with the 'loop'
- var escapemark: nullable EscapeMark
- redef fun accept_scope_visitor(v)
- do
- var escapemark = v.make_escape_mark(n_label, true)
- self.escapemark = escapemark
- v.enter_visit_block(n_block, escapemark)
- end
-end
-
-redef class AForExpr
- # The automatic variables in order
- var variables: nullable Array[Variable]
-
- # The escape mark associated with the 'for'
- var escapemark: nullable EscapeMark
-
- redef fun accept_scope_visitor(v)
- do
- v.enter_visit(n_expr)
-
- # Protect automatic variables
- v.scopes.unshift(new Scope)
-
- # Create the automatic variables
- var variables = new Array[Variable]
- self.variables = variables
- for nid in n_ids do
- var va = new Variable(nid.text)
- v.register_variable(nid, va)
- variables.add(va)
- end
-
- var escapemark = v.make_escape_mark(n_label, true)
- self.escapemark = escapemark
- v.enter_visit_block(n_block, escapemark)
-
- v.scopes.shift
- end
-end
-
-redef class AVarFormExpr
- # The associated variable
- var variable: nullable Variable
-end
-
-redef class ACallFormExpr
- redef fun accept_scope_visitor(v)
- do
- if n_expr isa AImplicitSelfExpr then
- var name = n_id.text
- var variable = v.search_variable(name)
- if variable != null then
- var n: AExpr
- if not n_args.n_exprs.is_empty or n_args isa AParExprs then
- v.error(self, "Error: {name} is variable, not a function.")
- return
- end
- n = variable_create(variable)
- n.variable = variable
- replace_with(n)
- n.accept_scope_visitor(v)
- return
- end
- end
-
- super
- end
-
- # Create a variable acces corresponding to the call form
- private fun variable_create(variable: Variable): AVarFormExpr is abstract
-end
-
-redef class ACallExpr
- redef fun variable_create(variable)
- do
- return new AVarExpr.init_avarexpr(n_id)
- end
-end
-
-redef class ACallAssignExpr
- redef fun variable_create(variable)
- do
- return new AVarAssignExpr.init_avarassignexpr(n_id, n_assign, n_value)
- end
-end
-
-redef class ACallReassignExpr
- redef fun variable_create(variable)
- do
- return new AVarReassignExpr.init_avarreassignexpr(n_id, n_assign_op, n_value)
- end
-end
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