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Phase for making identifiers globally unique #178

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acdf0a5
Generalized scope handling in visitors
jenrik May 19, 2019
b982d0b
New phase for makeing identifiers globally unique
jenrik May 19, 2019
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2 changes: 1 addition & 1 deletion compiler/src/main/kotlin/ast/ast.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -364,7 +364,7 @@ class NeighbourhoodDecl(
*/
class FunctionArgument(
ctx: SourceContext,
val ident: String,
var ident: String,
val type: Type = UncheckedType
) : AST(ctx)

Expand Down
114 changes: 114 additions & 0 deletions compiler/src/main/kotlin/visitors/Uniqueify.kt
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@@ -0,0 +1,114 @@
package dk.aau.cs.d409f19.cellumata.visitors

import com.ibm.icu.text.SymbolTable
import com.sun.xml.internal.fastinfoset.algorithm.BuiltInEncodingAlgorithm
import dk.aau.cs.d409f19.cellumata.ast.*
import dk.aau.cs.d409f19.cellumata.visitors.codegen.InvalidIdentLookupError
import java.util.Stack

/**
* Makes all identifiers unique. This elements need keep track of scoping in some cases.
*
* Prerequisites: The ScopeChecker must be run prior to this phase. We to make sure that redeclaration doesn't occur.
*/
class Uniqueify(oldSymbolTable: Table, newSymbolTable: Table = Table()): BaseScopedASTVisitor() {
private var viewingSymbolTableSession = ViewingSymbolTableSession(oldSymbolTable)
private var creatingSymbolTabelSession = CreatingSymbolTableSession(newSymbolTable)
private val mappings: Stack<Map<String, String>> = Stack()
private var labelCounter = 0

override fun openScope() {
viewingSymbolTableSession.openScope()
creatingSymbolTabelSession.openScope()
}

override fun closeScope() {
viewingSymbolTableSession.closeScope()
creatingSymbolTabelSession.closeScope()
}

init {
mappings.push(mapOf()) // Global scope
}

private fun nextLabel(): String {
return "label_${labelCounter++}"
}

/**
* @param ident Identifier
* @return The mapped label for the identifier
*/
private fun addMapping(ident: String): String {
// Change the map object at the top of the stack
val label = nextLabel()
creatingSymbolTabelSession.insertSymbol(
label,
viewingSymbolTableSession.getSymbol(ident)!!
)
mappings.push(mappings.pop() + Pair(ident, label))
System.out.println("Uniqueify: mapped $ident to $label") // ToDo use a proper logging system
return label
}

private fun getMappedLabel(ident: String): String {
for (scope in mappings.reversed()) {
if (scope.containsKey(ident)) {
val label = scope.getValue(ident)
System.out.println("Uniqueify: Found mapping from $ident to $label")
return label
}
}

System.out.println("Uniqueify: No mapping for $ident")
throw InvalidIdentLookupError()
}

fun getSymbolTable(): Table {
return creatingSymbolTabelSession.getRootTable()
}

override fun visit(node: RootNode) {
node.body.forEach {
when (it) {
is ConstDecl -> it.ident = addMapping(it.ident)
is StateDecl -> it.ident = addMapping(it.ident)
is NeighbourhoodDecl -> it.ident = addMapping(it.ident)
is FuncDecl -> it.ident = addMapping(it.ident)
}
}

super.visit(node)
}

override fun visit(node: Identifier) {
node.spelling = getMappedLabel(node.spelling)

super.visit(node)
}

override fun visit(node: FuncCallExpr) {
// Ignore builtin functions, their names are already unique
if (viewingSymbolTableSession.getSymbol(node.ident) !is BuiltinFunc) {
node.ident = getMappedLabel(node.ident)
}

super.visit(node)
}

override fun visit(node: AssignStmt) {
node.ident = if (node.isDeclaration) {
addMapping(node.ident)
} else {
getMappedLabel(node.ident)
}

super.visit(node)
}

override fun visit(node: FunctionArgument) {
node.ident = addMapping(node.ident)

super.visit(node)
}
}
55 changes: 10 additions & 45 deletions compiler/src/main/kotlin/visitors/symbolchecker.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ class UndeclaredNameException(ctx: SourceContext, val ident: String) : CompileEr
/**
* Walks through the abstract syntax tree, extracts symbols, and checks for use-before-declaration.
*/
class ScopeCheckVisitor(symbolTable: Table = Table()) : BaseASTVisitor() {
class ScopeCheckVisitor(symbolTable: Table = Table()) : BaseScopedASTVisitor() {
private val symbolTableSession: CreatingSymbolTableSession = CreatingSymbolTableSession(symbolTable = symbolTable)

/**
Expand All @@ -22,6 +22,14 @@ class ScopeCheckVisitor(symbolTable: Table = Table()) : BaseASTVisitor() {
return symbolTableSession.getRootTable()
}

override fun openScope() {
symbolTableSession.openScope()
}

override fun closeScope() {
symbolTableSession.closeScope()
}

override fun visit(node: RootNode) {
// Extract all states, functions, and neighbourhoods names first
node.body.filter { it is StateDecl }.forEach { symbolTableSession.insertSymbol((it as StateDecl).ident, it) }
Expand Down Expand Up @@ -52,18 +60,8 @@ class ScopeCheckVisitor(symbolTable: Table = Table()) : BaseASTVisitor() {
symbolTableSession.insertSymbol(node.ident, node)
}

override fun visit(node: StateDecl) {
symbolTableSession.openScope()
super.visit(node)
symbolTableSession.closeScope()
}

override fun visit(node: FuncDecl) {
symbolTableSession.openScope()
override fun visitFuncDeclPreNode(node: FuncDecl) {
node.args.forEach { symbolTableSession.insertSymbol(it.ident, it) }

super.visit(node)
symbolTableSession.closeScope()
}

override fun visit(node: AssignStmt) {
Expand All @@ -81,43 +79,10 @@ class ScopeCheckVisitor(symbolTable: Table = Table()) : BaseASTVisitor() {
super.visit(node)
}

override fun visit(node: IfStmt) {
// conditional blocks open their own scopes
node.conditionals.forEach { visit(it) }
if (node.elseBlock != null) {
symbolTableSession.openScope()
visit(node.elseBlock)
symbolTableSession.closeScope()
}
}

override fun visit(node: ConditionalBlock) {
visit(node.expr)
symbolTableSession.openScope()
visit(node.block)
symbolTableSession.closeScope()
}

override fun visit(node: FuncCallExpr) {
if (symbolTableSession.getSymbol(node.ident) == null) {
ErrorLogger += UndeclaredNameException(node.ctx, node.ident)
}
super.visit(node)
}

override fun visit(node: ForLoopStmt) {
// For-loop adds two layers of scopes.
// In the outer-layer are the init, condition, and post-iteration.
// The inner-layer is the loops body.
// This way any loop-control-variables (those in the init-part) are not remade every iteration, but they are
// removed when the loop finishes.
symbolTableSession.openScope()
node.initPart?.let { visit(it) }
visit(node.condition)
symbolTableSession.openScope()
visit(node.body)
symbolTableSession.closeScope()
node.postIterationPart?.let { visit(it) }
symbolTableSession.closeScope()
}
}
124 changes: 107 additions & 17 deletions compiler/src/main/kotlin/visitors/visitor.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -424,40 +424,130 @@ abstract class BaseASTVisitor: ASTVisitor<Unit> {
}
}

/**
* Walks the tree while opening and closing scopes as they are entered and left.
*
* @see BaseASTVisitor
*/
open class ScopedASTVisitor(symbolTable: Table): BaseASTVisitor() {
protected val symbolTableSession = ViewingSymbolTableSession(symbolTable = symbolTable)
abstract class BaseScopedASTVisitor : BaseASTVisitor() {
abstract fun openScope()
abstract fun closeScope()

override fun visit(node: StateDecl) {
symbolTableSession.openScope()
openScope()
visitStateDeclPreNode(node)
super.visit(node)
symbolTableSession.closeScope()
visitStateDeclPostNode(node)
closeScope()
}

open fun visitStateDeclPreNode(node: StateDecl) {}

open fun visitStateDeclPostNode(node: StateDecl) {}

override fun visit(node: FuncDecl) {
symbolTableSession.openScope()
openScope()
visitFuncDeclPreNode(node)
super.visit(node)
symbolTableSession.closeScope()
visitFuncDeclPostNode(node)
closeScope()
}

open fun visitFuncDeclPreNode(node: FuncDecl) {}

open fun visitFuncDeclPostNode(node: FuncDecl) {}

override fun visit(node: IfStmt) {
// conditional blocks open their own scopes
visitIfStmtPreConditionals()
node.conditionals.forEach { visit(it) }
visitIfStmtPostConditionals()
if (node.elseBlock != null) {
openScope()
visitIfStmtPreElseBlock()
visit(node.elseBlock)
visitIfStmtPostElseBlock()
closeScope()
}
}

open fun visitIfStmtPreConditionals() {}

open fun visitIfStmtPostConditionals() {}

open fun visitIfStmtPreElseBlock() {}

open fun visitIfStmtPostElseBlock() {}

override fun visit(node: ConditionalBlock) {
symbolTableSession.openScope()
super.visit(node)
symbolTableSession.closeScope()
visitConditionalBlockPreExpr(node)
visit(node.expr)
visitConditionalBlockPostExpr(node)
openScope()
visitConditionalBlockPreBlock(node)
visit(node.block)
visitConditionalBlockPostBlock(node)
closeScope()
}

open fun visitConditionalBlockPreExpr(node: ConditionalBlock) {}

open fun visitConditionalBlockPostExpr(node: ConditionalBlock) {}

open fun visitConditionalBlockPreBlock(node: ConditionalBlock) {}

open fun visitConditionalBlockPostBlock(node: ConditionalBlock) {}


override fun visit(node: ForLoopStmt) {
symbolTableSession.openScope()
// For-loop adds two layers of scopes.
// In the outer-layer are the init, condition, and post-iteration.
// The inner-layer is the loops body.
// This way any loop-control-variables (those in the init-part) are not remade every iteration, but they are
// removed when the loop finishes.
openScope()
visitForLoopPreInitPart(node)
node.initPart?.let { visit(it) }
visitForLoopPostInitPart(node)
visitForLoopPreCondition(node)
visit(node.condition)
symbolTableSession.openScope()
visitForLoopPostCondition(node)
openScope()
visitForLoopPreBody(node)
visit(node.body)
symbolTableSession.closeScope()
visitForLoopPostBody(node)
closeScope()
visitForLoopPrePostIteration(node)
node.postIterationPart?.let { visit(it) }
visitForLoopPostPostIteration(node)
closeScope()
}

open fun visitForLoopPreInitPart(node: ForLoopStmt) {}

open fun visitForLoopPostInitPart(node: ForLoopStmt) {}

open fun visitForLoopPreCondition(node: ForLoopStmt) {}

open fun visitForLoopPostCondition(node: ForLoopStmt) {}

open fun visitForLoopPreBody(node: ForLoopStmt) {}

open fun visitForLoopPostBody(node: ForLoopStmt) {}

open fun visitForLoopPrePostIteration(node: ForLoopStmt) {}

open fun visitForLoopPostPostIteration(node: ForLoopStmt) {}
}

/**
* Walks the tree while opening and closing scopes as they are entered and left.
*
* @see BaseASTVisitor
*/
open class ScopedASTVisitor(symbolTable: Table): BaseScopedASTVisitor() {
protected val symbolTableSession = ViewingSymbolTableSession(symbolTable = symbolTable)

override fun openScope() {
symbolTableSession.openScope()
}

override fun closeScope() {
symbolTableSession.closeScope()
}
}