| /* |
| * Copyright 2011 Google Inc. |
| * |
| * 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 com.google.gwt.codegen.server; |
| |
| /** |
| * Helper class to produce string expressions consisting of literals and |
| * computed values. |
| */ |
| public abstract class StringGenerator { |
| |
| /** |
| * Type of expression being processed. |
| */ |
| protected enum Type { |
| LITERAL, |
| PRIMITIVE, |
| SAFE, |
| OTHER, |
| } |
| |
| /** |
| * Create a {@link StringGenerator} instance. |
| * |
| * @param buf |
| * @param returnsSafeHtml |
| * @return {@link StringGenerator} instance |
| */ |
| public static StringGenerator create(StringBuilder buf, boolean returnsSafeHtml) { |
| if (returnsSafeHtml) { |
| return new SafeHtmlStringGenerator(buf); |
| } else { |
| return new PlainStringGenerator(buf); |
| } |
| } |
| |
| /** |
| * Output string buffer. |
| */ |
| protected final StringBuilder buf; |
| |
| /** |
| * True if we are in the middle of a string literal. |
| */ |
| protected boolean inString; |
| |
| /** |
| * Initialize the StringGenerator with an output buffer. |
| * |
| * @param buf output buffer |
| */ |
| protected StringGenerator(StringBuilder buf) { |
| this.buf = buf; |
| inString = false; |
| } |
| /** |
| * Append an expression to this string expression. |
| * |
| * @param expression to add |
| * @param isSafeHtmlTyped true if the expression is known to be of type |
| * {@link com.google.gwt.safehtml.shared.SafeHtml SafeHtml}; only relevant |
| * if this generator has been initialized to generate a |
| * {@link com.google.gwt.safehtml.shared.SafeHtml SafeHtml}-valued |
| * expression |
| * @param isPrimitiveTyped true if the expression is of a primitive type; |
| * only relevant if this generator has been initialized to generate a |
| * {@link com.google.gwt.safehtml.shared.SafeHtml SafeHtml}-valued |
| * expression |
| * @param needsConversionToString true if the expression is not known to be |
| * of type String and needs to be converted |
| */ |
| public void appendExpression(String expression, boolean isSafeHtmlTyped, |
| boolean isPrimitiveTyped, boolean needsConversionToString) { |
| if (inString) { |
| buf.append('"'); |
| afterExpression(Type.LITERAL); |
| inString = false; |
| } |
| Type type; |
| if (isPrimitiveTyped) { |
| type = Type.PRIMITIVE; |
| } else if (isSafeHtmlTyped) { |
| type = Type.SAFE; |
| } else { |
| type = Type.OTHER; |
| } |
| beforeExpression(type); |
| if (type == Type.OTHER && needsConversionToString) { |
| forceStringPrefix(); |
| } |
| buf.append(expression); |
| if (type == Type.OTHER && needsConversionToString) { |
| forceStringSuffix(); |
| } |
| afterExpression(type); |
| } |
| |
| /** |
| * Append part of a string literal. |
| * |
| * @param str part of string literal |
| */ |
| public void appendStringLiteral(String str) { |
| if (!inString) { |
| beforeExpression(Type.LITERAL); |
| buf.append('"'); |
| inString = true; |
| } |
| buf.append(str); |
| } |
| |
| /** |
| * Append an expression to this string expression. |
| * |
| * @param expression to add, which the caller asserts is String-valued |
| */ |
| public void appendStringValuedExpression(String expression) { |
| appendExpression(expression, false, false, false); |
| } |
| |
| /** |
| * Complete the string, closing an open quote and handling empty strings. |
| */ |
| public void completeString() { |
| if (inString) { |
| buf.append('"'); |
| afterExpression(Type.LITERAL); |
| } |
| finishOutput(); |
| } |
| |
| protected abstract void afterExpression(Type type); |
| |
| protected abstract void beforeExpression(Type type); |
| |
| protected abstract void finishOutput(); |
| |
| protected abstract void forceStringPrefix(); |
| |
| protected abstract void forceStringSuffix(); |
| } |