org.jetbrains.kotlin.backend.common.lower.StringConcatenationLowering.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2017 JetBrains s.r.o.
*
* 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.
*/
package org.jetbrains.kotlin.backend.common.lower
import org.jetbrains.kotlin.backend.common.CommonBackendContext
import org.jetbrains.kotlin.backend.common.FileLoweringPass
import org.jetbrains.kotlin.backend.common.atMostOne
import org.jetbrains.kotlin.ir.IrStatement
import org.jetbrains.kotlin.ir.builders.*
import org.jetbrains.kotlin.ir.declarations.*
import org.jetbrains.kotlin.ir.expressions.IrExpression
import org.jetbrains.kotlin.ir.expressions.IrStringConcatenation
import org.jetbrains.kotlin.ir.types.IrType
import org.jetbrains.kotlin.ir.types.isNullable
import org.jetbrains.kotlin.ir.types.isNullableAny
import org.jetbrains.kotlin.ir.util.constructors
import org.jetbrains.kotlin.ir.util.functions
import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
import org.jetbrains.kotlin.name.Name
/**
* This lowering pass replaces [IrStringConcatenation]s with StringBuilder appends.
*/
class StringConcatenationLowering(val context: CommonBackendContext) : FileLoweringPass {
override fun lower(irFile: IrFile) {
irFile.transformChildrenVoid(StringConcatenationTransformer(this))
}
}
private class StringConcatenationTransformer(val lower: StringConcatenationLowering) : IrElementTransformerVoid() {
private val buildersStack = mutableListOf()
private val context = lower.context
private val irBuiltIns = context.irBuiltIns
private val typesWithSpecialAppendFunction = irBuiltIns.primitiveIrTypes + irBuiltIns.stringType
private val nameToString = Name.identifier("toString")
private val nameAppend = Name.identifier("append")
private val stringBuilder = context.ir.symbols.stringBuilder.owner
//TODO: calculate and pass string length to the constructor.
private val constructor = stringBuilder.constructors.single {
it.valueParameters.size == 0
}
private val toStringFunction = stringBuilder.functions.single {
it.valueParameters.size == 0 && it.name == nameToString
}
private val defaultAppendFunction = stringBuilder.functions.single {
it.name == nameAppend &&
it.valueParameters.size == 1 &&
it.valueParameters.single().type.isNullableAny()
}
private val appendFunctions: Map =
typesWithSpecialAppendFunction.map { type ->
type to stringBuilder.functions.toList().atMostOne {
it.name == nameAppend && it.valueParameters.singleOrNull()?.type == type
}
}.toMap()
private fun typeToAppendFunction(type: IrType): IrSimpleFunction {
return appendFunctions[type] ?: defaultAppendFunction
}
override fun visitStringConcatenation(expression: IrStringConcatenation): IrExpression {
assert(!buildersStack.isEmpty())
expression.transformChildrenVoid(this)
val blockBuilder = buildersStack.last()
val arguments = expression.arguments
return when (arguments.size) {
0 -> blockBuilder.irString("")
1 -> {
val argument = arguments[0]
if (argument.type.isNullable())
blockBuilder.irCall(context.ir.symbols.extensionToString).apply {
extensionReceiver = argument
}
else blockBuilder.irCall(
context.irBuiltIns.anyClass.functions
.single { it.owner.name.asString() == "toString" }).apply {
dispatchReceiver = argument
}
}
else -> {
blockBuilder.irBlock(expression) {
val stringBuilderImpl = createTmpVariable(irCall(constructor))
expression.arguments.forEach { arg ->
val appendFunction = typeToAppendFunction(arg.type)
+irCall(appendFunction).apply {
dispatchReceiver = irGet(stringBuilderImpl)
putValueArgument(0, arg)
}
}
+irCall(toStringFunction).apply {
dispatchReceiver = irGet(stringBuilderImpl)
}
}
}
}
}
override fun visitDeclaration(declaration: IrDeclarationBase): IrStatement {
if (declaration !is IrSymbolDeclaration<*>) {
return super.visitDeclaration(declaration)
}
with(declaration) {
buildersStack.add(
context.createIrBuilder(declaration.symbol, startOffset, endOffset)
)
transformChildrenVoid(this@StringConcatenationTransformer)
buildersStack.removeAt(buildersStack.lastIndex)
return this@with
}
}
}