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Eclipse Compiler for Java(TM)
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/*******************************************************************************
 * Copyright (c) 2000, 2024 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;

import org.eclipse.jdt.internal.compiler.ASTVisitor;
import org.eclipse.jdt.internal.compiler.codegen.CodeStream;
import org.eclipse.jdt.internal.compiler.impl.StringConstant;
import org.eclipse.jdt.internal.compiler.lookup.BlockScope;
import org.eclipse.jdt.internal.compiler.lookup.TypeBinding;
import org.eclipse.jdt.internal.compiler.util.Util;

public class StringLiteral extends Literal {

	/** may be null, prefixes tail **/
	protected StringLiteral optionalHead;
	/** StringLiteral or char[] tail **/
	protected Object tail;
	/** zero based **/
	private final int lineNumber;

	public StringLiteral(char[] token, int start, int end, int lineNumber1based) {
		this(null, token, start, end, lineNumber1based - 1);
	}

	protected StringLiteral(StringLiteral optionalHead, Object tail, int start, int end, int lineNumber) {
		super(start, end);
		this.optionalHead = optionalHead;
		this.tail = tail;
		this.lineNumber = lineNumber;
	}

	public StringLiteral(int s, int e) {
		this(null, null, s, e, 0);
	}

	@Override
	public void computeConstant() {
		this.constant = StringConstant.fromValue(String.valueOf(this.source()));
	}

	/**
	 * creates a copy of dedicated Type for optimizeStringLiterals with the given CharLiteral appended
	 */
	public ExtendedStringLiteral extendWith(CharLiteral lit) {
		char[] charTail = new char[] { lit.value };
		return new ExtendedStringLiteral(this, charTail, this.sourceStart, lit.sourceEnd, this.getLineNumber());
	}

	/**
	 * creates a copy of dedicated Type for optimizeStringLiterals with the given StringLiteral appended
	 */
	public ExtendedStringLiteral extendWith(StringLiteral lit) {
		return new ExtendedStringLiteral(this, lit, this.sourceStart, lit.sourceEnd, this.getLineNumber());
	}

	/**
	 * creates a copy of dedicated Type for unoptimizeStringLiterals with the given StringLiteral appended
	 */
	public StringLiteralConcatenation extendsWith(StringLiteral lit) {
		return new StringLiteralConcatenation(this, lit);
	}

	/**
	 * Code generation for string literal
	 */
	@Override
	public void generateCode(BlockScope currentScope, CodeStream codeStream, boolean valueRequired) {
		int pc = codeStream.position;
		if (valueRequired)
			codeStream.ldc(this.constant.stringValue());
		codeStream.recordPositionsFrom(pc, this.sourceStart);
	}

	@Override
	public TypeBinding literalType(BlockScope scope) {
		return scope.getJavaLangString();
	}

	@Override
	public StringBuilder printExpression(int indent, StringBuilder output) {
		// handle some special char.....
		output.append('\"');
		for (char s : source()) {
			Util.appendEscapedChar(output, s, true);
		}
		output.append('\"');
		return output;
	}

	@Override
	public char[] source() {
		if (this.optionalHead == null && this.tail instanceof char[] ch) {
			// fast path without copy
			return ch;
		}
		// flatten linked list to char[]
		int size = append(null, 0, this);
		char[] result = new char[size];
		append(result, 0, this);
		flatten(result);
		return result;
	}

	protected void flatten(char[] result) {
		setSource(result); // keep flat version
	}

	private static int append(char[] result, int length, StringLiteral o) {
		do {
			if (o.tail instanceof char[] c) {
				if (result != null) {
					System.arraycopy(c, 0, result, result.length - c.length - length, c.length);
				}
				length += c.length;
			} else {
				length = append(result, length, ((StringLiteral) o.tail));
			}
			o = o.optionalHead;
		} while (o != null);
		return length;
	}

	@Override
	public void traverse(ASTVisitor visitor, BlockScope scope) {
		visitor.visit(this, scope);
		visitor.endVisit(this, scope);
	}

	public void setSource(char[] source) {
		this.tail = source;
		this.optionalHead = null;
	}

	public int getLineNumber() {
		return this.lineNumber;
	}
}