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30 day Evaluation Version distributed via the Maven Jar Repository. Clover is not free. You have 30 days to evaluate it. Please visit http://www.thecortex.net/clover to obtain a licensed version of Clover | |||||||||||||||||||
Source file | Conditionals | Statements | Methods | TOTAL | |||||||||||||||
SymbolExpander.java | 100% | 100% | 100% | 100% |
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// Copyright 2004 The Apache Software Foundation
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package org.apache.hivemind.impl;
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import org.apache.hivemind.ErrorHandler;
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import org.apache.hivemind.Location;
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import org.apache.hivemind.SymbolSource;
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/**
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* A simple parser used to identify symbols in a string and expand them via
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* a {@link org.apache.hivemind.SymbolSource}.
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*
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* @author Howard Lewis Ship
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*/
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public class SymbolExpander |
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{ |
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private ErrorHandler _errorHandler;
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private SymbolSource _source;
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public SymbolExpander(ErrorHandler handler, SymbolSource source)
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{ |
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_errorHandler = handler; |
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_source = source; |
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} |
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private static final Log LOG = LogFactory.getLog(SymbolExpander.class); |
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private static final int STATE_START = 0; |
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private static final int STATE_DOLLAR = 1; |
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private static final int STATE_COLLECT_SYMBOL_NAME = 2; |
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/**
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* <p>Identifies symbols in the text and expands them, using the
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* {@link SymbolSource}. Returns the modified text. May return text if text
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* does not contain any symbols.
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*
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* @param text the text to scan
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* @param location the location to report errors (undefined symbols)
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*
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* Note: a little cut-n-paste from {@link org.apache.tapestry.script.AbstractTokenRule}.
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*/
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public String expandSymbols(String text, Location location)
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{ |
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StringBuffer result = new StringBuffer(text.length());
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char[] buffer = text.toCharArray();
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int state = STATE_START;
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int blockStart = 0;
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int blockLength = 0;
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int symbolStart = -1;
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int symbolLength = 0;
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int i = 0;
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int braceDepth = 0;
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boolean anySymbols = false; |
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while (i < buffer.length)
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{ |
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char ch = buffer[i];
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switch (state)
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{ |
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case STATE_START :
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if (ch == '$')
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{ |
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state = STATE_DOLLAR; |
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i++; |
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continue;
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} |
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blockLength++; |
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i++; |
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continue;
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case STATE_DOLLAR :
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if (ch == '{')
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{ |
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state = STATE_COLLECT_SYMBOL_NAME; |
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i++; |
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symbolStart = i; |
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symbolLength = 0; |
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braceDepth = 1; |
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continue;
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} |
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// Any time two $$ appear, it is collapsed down to a single $,
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// but the next character is passed through un-interpreted (even if it
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// is a brace).
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if (ch == '$')
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{ |
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// This is effectively a symbol, meaning that the input string
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// will not equal the output string.
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anySymbols = true;
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if (blockLength > 0)
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result.append(buffer, blockStart, blockLength); |
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result.append(ch); |
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i++; |
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blockStart = i; |
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blockLength = 0; |
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state = STATE_START; |
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continue;
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} |
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// The '$' was just what it was, not the start of a ${} expression
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// block, so include it as part of the static text block.
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blockLength++; |
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state = STATE_START; |
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continue;
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case STATE_COLLECT_SYMBOL_NAME :
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if (ch != '}')
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{ |
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if (ch == '{')
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braceDepth++; |
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i++; |
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symbolLength++; |
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continue;
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} |
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braceDepth--; |
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if (braceDepth > 0)
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{ |
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i++; |
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symbolLength++; |
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continue;
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} |
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// Hit the closing brace of a symbol.
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// Degenerate case: the string "${}".
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if (symbolLength == 0)
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blockLength += 3; |
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// Append anything up to the start of the sequence (this is static
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// text between symbol references).
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if (blockLength > 0)
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result.append(buffer, blockStart, blockLength); |
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if (symbolLength > 0)
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{ |
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String variableName = |
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text.substring(symbolStart, symbolStart + symbolLength); |
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result.append(expandSymbol(variableName, location)); |
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anySymbols = true;
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} |
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i++; |
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blockStart = i; |
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blockLength = 0; |
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// And drop into state start
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state = STATE_START; |
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continue;
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} |
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} |
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// If get this far without seeing any variables, then just pass
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// the input back.
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if (!anySymbols)
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return text;
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// OK, to handle the end. Couple of degenerate cases where
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// a ${...} was incomplete, so we adust the block length.
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if (state == STATE_DOLLAR)
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blockLength++; |
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if (state == STATE_COLLECT_SYMBOL_NAME)
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blockLength += symbolLength + 2; |
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if (blockLength > 0)
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result.append(buffer, blockStart, blockLength); |
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return result.toString();
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} |
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private String expandSymbol(String name, Location location)
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{ |
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String value = _source.valueForSymbol(name); |
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if (value != null) |
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return value;
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_errorHandler.error(LOG, ImplMessages.noSuchSymbol(name), location, null);
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return "${" + name + "}"; |
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} |
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} |
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