Add calculator plugin

Change-Id: I3372fcf5db4539d21192d663caaa052394377a2c
Reviewed-on: http://gerrit.dmdirc.com/276
Reviewed-by: Shane Mc Cormack <shane@dmdirc.com>
Tested-by: Gregory Holmes <greboid@dmdirc.com>

src/com/dmdirc/addons/calc/CalcCommand.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import com.dmdirc.commandparser.CommandArguments;
+import com.dmdirc.commandparser.commands.GlobalCommand;
+import com.dmdirc.ui.interfaces.InputWindow;
+import java.text.ParseException;
+
+/**
+ * A command which allows users to evaluate various mathematical expressions,
+ * and perform basic calculations.
+ *
+ * @author chris
+ */
+public class CalcCommand extends GlobalCommand {
+
+    /** {@inheritDoc} */
+    @Override
+    public void execute(final InputWindow origin, final boolean isSilent,
+            final CommandArguments args) {
+        try {
+            int offset = 0;
+            boolean showexpr = false;
+
+            if (args.getArguments().length > 0 && args.getArguments()[0].equals("--showexpr")) {
+                showexpr = true;
+                offset++;
+            }
+
+            final String input = args.getArgumentsAsString(offset);
+            final Lexer lexer = new Lexer(input);
+            final Parser parser = new Parser(lexer);
+            final Evaluator evaluator = new Evaluator(parser.parse());
+            final Number result = evaluator.evaluate();
+            sendLine(origin, isSilent, FORMAT_OUTPUT,
+                    (showexpr ? input + " = " : "") + result);
+        } catch (ParseException ex) {
+            sendLine(origin, isSilent, FORMAT_ERROR, "Unable to parse expression: "
+                    + ex.getMessage());
+        } catch (ArithmeticException ex) {
+            sendLine(origin, isSilent, FORMAT_ERROR, "Unable to calculate expression: "
+                    + ex.getMessage());
+        }
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public String getName() {
+        return "calc";
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public boolean showInHelp() {
+        return true;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public String getHelp() {
+        return "calc [--showexpr] <expr> - evaluate mathematical expression";
+    }
+}

src/com/dmdirc/addons/calc/CalcCommandInfo.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import com.dmdirc.commandparser.CommandInfo;
+import com.dmdirc.commandparser.CommandType;
+
+/**
+ * Calc command info.
+ *
+ * @author chris
+ */
+public class CalcCommandInfo implements CommandInfo {
+
+    /** {@inheritDoc} */
+    @Override
+    public String getName() {
+        return "calc";
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public boolean showInHelp() {
+        return true;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public String getHelp() {
+        return "calc [--showexpr] <expr> - evaluate mathematical expression";
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public CommandType getType() {
+        return CommandType.TYPE_GLOBAL;
+    }
+}

src/com/dmdirc/addons/calc/CalcPlugin.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import com.dmdirc.commandparser.CommandManager;
+import com.dmdirc.plugins.Plugin;
+
+/**
+ * A plugin which parses and evaluates various mathematical expressions.
+ * 
+ * @author chris
+ */
+public class CalcPlugin extends Plugin {
+
+    /** The command we register when loaded. */
+    private final CalcCommand command = new CalcCommand();
+    /** The CommandInfo object describing the calc command. */
+    private final CalcCommandInfo commandInfo = new CalcCommandInfo();
+
+    /** {@inheritDoc} */
+    @Override
+    public void onLoad() {
+        CommandManager.registerCommand(command, commandInfo);
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public void onUnload() {
+        CommandManager.unregisterCommand(commandInfo);
+    }
+
+}

src/com/dmdirc/addons/calc/DotOutputter.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import java.text.ParseException;
+
+/**
+ * Outputs a string which can be read by the unix `dot` utility to show a
+ * directed graph showing the tokens parsed by a {@link Parser}.
+ *
+ * @author chris
+ */
+public class DotOutputter {
+
+    /** The parser which will be read. */
+    private final Parser parser;
+
+    /** Counter for assigning node IDs. */
+    private int nodes = 0;
+
+    /**
+     * Creates a new DotOutputter for the specified parser.
+     *
+     * @param parser The parser whose output should be shown
+     */
+    public DotOutputter(final Parser parser) {
+        this.parser = parser;
+    }
+
+    /**
+     * Outputs a string which may be read by the `dot` utility to create a
+     * directed graph of tokens.
+     *
+     * @return A string describing the parse tree from the specified parser
+     * @throws ParseException If the parser encounters an exception
+     */
+    public String output() throws ParseException {
+        return "digraph astoutput { " + output(0, parser.parse()) + " }";
+    }
+
+    /**
+     * Outputs the relevant text for the specified token, assigning it an ID
+     * specified by the node parameter.
+     *
+     * @param node The ID of the node to be used in the output
+     * @param token The token to be outputted
+     * @return A string corresponding to the dot representation of the
+     * specified node and its children
+     */
+    protected String output(final int node, final TreeToken token) {
+        String out = "node" + node + " [label=\"" + token.getToken().getType()
+                + "\\n" + token.getToken().getContent() + "\"];";
+
+        for (TreeToken child : token.getChildren()) {
+            int id = ++nodes;
+
+            out += output(id, child);
+            out += "node" + node + " -> node" + id + ";";
+        }
+
+        return out;
+    }
+
+}

src/com/dmdirc/addons/calc/Evaluator.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+/**
+ * A simple evaluator which just requests that the {@link TreeToken} evaluates
+ * itself.
+ *
+ * @author chris
+ */
+public class Evaluator {
+
+    /** The token to be evaluated. */
+    private final TreeToken node;
+
+    /**
+     * Creates a new evaluator for the specified token.
+     *
+     * @param node The token to be evaluated
+     */
+    public Evaluator(final TreeToken node) {
+        this.node = node;
+    }
+
+    /**
+     * Evaluates the token and returns the numeric result.
+     *
+     * @return The numeric result of evaluation
+     */
+    public Number evaluate() {
+        return node.evaluate();
+    }
+
+}

src/com/dmdirc/addons/calc/Lexer.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * The lexer takes a String input and produces an ordered list of {@link Token}s
+ * corresponding to the input.
+ *
+ * @author chris
+ */
+public class Lexer {
+
+    /** The input string. */
+    final String input;
+
+    /**
+     * Creates a new lexer for the specified input string.
+     *
+     * @param input The string to be tokenised
+     */
+    public Lexer(final String input) {
+        this.input = input.replaceAll("\\s+", "");
+    }
+
+    /**
+     * Tokenises the input string into an ordered list of tokens.
+     *
+     * @return A list of tokens corresponding to the input string
+     * @throws ParseException If an expected token is not found
+     */
+    public List<Token> tokenise() throws ParseException {
+        final List<Token> res = new ArrayList<Token>();
+        List<TokenType> possibles = Arrays.asList(TokenType.values());
+
+        boolean cont = true;
+        int i = 0;
+
+        do {
+            boolean found = false;
+
+            for (TokenType type : possibles) {
+                final int match = type.match(input, i);
+
+                if (match > -1) {
+                    res.add(new Token(type, input.substring(i, match)));
+
+                    possibles = type.getFollowers();
+                    i = match;
+                    found = true;
+                    cont = type != TokenType.END;
+
+                    break;
+                }
+            }
+
+            if (!found) {
+                throw new ParseException("No legal token found at offset "
+                        + i + ". Expecting one of: "
+                        + Arrays.toString(possibles.toArray()), i);
+            }
+        } while (cont);
+
+        return res;
+    }
+
+}

src/com/dmdirc/addons/calc/Parser.java

@@ -0,0 +1,240 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * The parser takes the output from a {@link Lexer} and applies precdence rules
+ * to build the tokens into a tree.
+ *
+ * @author chris
+ */
+public class Parser {
+
+    /** The lexer whose output will be parsed. */
+    protected final Lexer lexer;
+    /** A list of token types sorted by their precendece. */
+    protected static final List<TokenType> TOKENS_BY_PRECEDENCE;
+
+    static {
+        TOKENS_BY_PRECEDENCE = new ArrayList<TokenType>(Arrays.asList(TokenType.values()));
+        Collections.sort(TOKENS_BY_PRECEDENCE, new TokenTypePrecedenceComparator());
+    }
+
+    /**
+     * Creates a new parser for the specified lexer.
+     *
+     * @param lexer The lexer whose output should be parsed
+     */
+    public Parser(final Lexer lexer) {
+        this.lexer = lexer;
+    }
+
+    /**
+     * Parses the output of this parser's lexer, and returns a {@link TreeToken}
+     * representing the parsed formula.
+     *
+     * @return A token tree corresponding to the lexer's token output
+     * @throws ParseException If the lexer encounters a parse error, or if an
+     * error occurs while parsing the lexer's output (such as a non-sensical
+     * formula such as one involving a mis-matched bracket).
+     */
+    public TreeToken parse() throws ParseException {
+        final List<TreeToken> tokens = new ArrayList<TreeToken>();
+
+        for (Token token : lexer.tokenise()) {
+            tokens.add(new TreeToken(token));
+        }
+
+        return parse(tokens);
+    }
+
+    /**
+     * Parses the specified tokens into a tree.
+     *
+     * @param tokens The tokens to be parsed
+     * @return A single tree containing all of the specified tokens
+     * @throws ParseException If the tokens contain mismatched brackets
+     */
+    protected TreeToken parse(final List<TreeToken> tokens) throws ParseException {
+        while (tokens.size() > 1) {
+            for (TokenType type : TOKENS_BY_PRECEDENCE) {
+                final int offset = findTokenType(tokens, type);
+
+                if (offset > -1) {
+                    switch (type.getArity()) {
+                        case HIDDEN:
+                            parseHiddenOperator(tokens, offset);
+                            break;
+                        case BINARY:
+                            parseBinaryOperator(tokens, offset);
+                            break;
+                        case UNARY:
+                            parseUnaryOperator(tokens, offset);
+                            break;
+                        case NULLARY:
+                            parseNullaryOperator(tokens, offset);
+                            break;
+                    }
+
+                    break;
+                }
+            }
+        }
+
+        return tokens.get(0);
+    }
+
+    /**
+     * Parses an operator that takes no operands.
+     *
+     * @param tokens The supply of tokens from which the operator will be parsed
+     * @param offset The offset at which the operator occurs
+     * @throws ParseException If the operator is a bracket and that bracket is
+     * mismatched
+     */
+    protected void parseNullaryOperator(final List<TreeToken> tokens, final int offset)
+            throws ParseException {
+        if (tokens.get(offset).getToken().getType() == TokenType.BRACKET_CLOSE
+                || tokens.get(offset).getToken().getType() == TokenType.BRACKET_OPEN) {
+            parseBracket(tokens, offset);
+        } else {
+            parseNumber(tokens, offset);
+        }
+    }
+
+    /**
+     * Parses a bracket operator.
+     *
+     * @param tokens The supply of tokens from which the operator will be parsed
+     * @param offset The offset at which the operator occurs
+     * @throws ParseException If the operator is a bracket and that bracket is
+     * mismatched
+     */
+    protected void parseBracket(final List<TreeToken> tokens, final int offset)
+            throws ParseException {
+        final List<TreeToken> stack = new ArrayList<TreeToken>();
+
+        for (int i = offset - 1; i > 0; i--) {
+            if (tokens.get(i).getToken().getType() == TokenType.BRACKET_OPEN
+                    && !tokens.get(i).isProcessed()) {
+                tokens.add(i, parse(stack));
+                tokens.get(i).setProcessed();
+                tokens.remove(i + 1);
+                tokens.remove(i + 1);
+                return;
+            } else {
+                stack.add(0, tokens.get(i));
+                tokens.remove(i);
+            }
+        }
+
+        throw new ParseException("Couldn't find matching opening bracket", offset);
+    }
+
+    /**
+     * Parses an operator that takes two operands.
+     *
+     * @param tokens The supply of tokens from which the operator will be parsed
+     * @param offset The offset at which the operator occurs
+     */
+    protected void parseBinaryOperator(final List<TreeToken> tokens, final int offset) {
+        tokens.get(offset).addChild(tokens.get(offset - 1));
+        tokens.get(offset).addChild(tokens.get(offset + 1));
+        tokens.get(offset).setProcessed();
+
+        tokens.remove(offset + 1);
+        tokens.remove(offset - 1);
+    }
+
+    /**
+     * Parses an operator that takes one operand.
+     *
+     * @param tokens The supply of tokens from which the operator will be parsed
+     * @param offset The offset at which the operator occurs
+     */
+    protected void parseUnaryOperator(final List<TreeToken> tokens, final int offset) {
+        tokens.get(offset).addChild(tokens.get(offset + 1));
+        tokens.get(offset).setProcessed();
+        tokens.remove(offset + 1);
+    }
+
+    /**
+     * Parses an operator that does not actually correspond to a piece of the
+     * input (such as the START and END operators).
+     *
+     * @param tokens The supply of tokens from which the operator will be parsed
+     * @param offset The offset at which the operator occurs
+     */
+    protected void parseHiddenOperator(final List<TreeToken> tokens, final int offset) {
+        tokens.remove(offset);
+    }
+
+    /**
+     * Parses a number.
+     *
+     * @param tokens The supply of tokens from which the operator will be parsed
+     * @param offset The offset at which the operator occurs
+     */
+    protected void parseNumber(final List<TreeToken> tokens, final int offset) {
+        tokens.get(offset).setProcessed();
+    }
+
+    /**
+     * Retrieves the offset of the first token within the input list that has
+     * a type corresponding to the specified {@link TokenType}.
+     *
+     * @param tokens The tokens to be searched
+     * @param type The desired token type
+     * @return The index of the first token with that type, or -1 if none found
+     */
+    protected static int findTokenType(final List<TreeToken> tokens, final TokenType type) {
+        for (int i = 0; i < tokens.size(); i++) {
+            if (tokens.get(i).getToken().getType() == type && !tokens.get(i).isProcessed()) {
+                return i;
+            }
+        }
+
+        return -1;
+    }
+
+    /**
+     * A class which compares token types based on their precendence.
+     */
+    protected static class TokenTypePrecedenceComparator implements Comparator<TokenType> {
+
+        /** {@inheritDoc} */
+        @Override
+        public int compare(final TokenType o1, final TokenType o2) {
+            return o2.getPrecedence() - o1.getPrecedence();
+        }
+
+    }
+
+}

src/com/dmdirc/addons/calc/Token.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+/**
+ * Describes a distinct piece of a mathematical formula, as tokenised by a
+ * {@link Lexer}.
+ *
+ * @author chris
+ */
+public class Token {
+
+    /** The type of this token. */
+    private final TokenType type;
+
+    /** The content of this token, if any. */
+    private final String content;
+
+    /**
+     * Creates a new token.
+     *
+     * @param type The type of the token
+     * @param content The content of the token
+     */
+    public Token(final TokenType type, final String content) {
+        this.type = type;
+        this.content = content;
+    }
+
+    /**
+     * Retrieves the content of this token.
+     *
+     * @return This token's content
+     */
+    public String getContent() {
+        return content;
+    }
+
+    /**
+     * Retrieves the type of this token.
+     *
+     * @return This token's type
+     */
+    public TokenType getType() {
+        return type;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public String toString() {
+        return "[type: " + type + "; content: " + content + "]";
+    }
+
+}

src/com/dmdirc/addons/calc/TokenType.java

@@ -0,0 +1,254 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Describes the different types of possible token, their arities, precedence,
+ * and the types of token that may follow them.
+ * 
+ * @author chris
+ */
+public enum TokenType {
+
+    /** The start of an input string. */
+    START(TokenTypeArity.HIDDEN, "^", 0, "NUMBER_*", "BRACKET_OPEN", "MOD_*"),
+    /** The end of an input string. */
+    END(TokenTypeArity.HIDDEN, "$", 0),
+
+    /** An opening bracket. */
+    BRACKET_OPEN(TokenTypeArity.NULLARY, "\\(", 0, "NUMBER_*", "MOD_*", "BRACKET_OPEN"),
+    /** A closing bracket. */
+    BRACKET_CLOSE(TokenTypeArity.NULLARY, "\\)", 50, "OP_*", "BRACKET_*", "END"),
+
+    /** A floating point number. */
+    NUMBER_FLOAT(TokenTypeArity.NULLARY, "[0-9]+\\.[0-9]+", 1, "OP_*", "BRACKET_*", "END") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return Float.valueOf(token.getToken().getContent());
+        }
+    },
+
+    /** An integer. */
+    NUMBER_INT(TokenTypeArity.NULLARY, "[0-9]+", 1, "OP_*", "BRACKET_*", "END") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return Float.valueOf(token.getToken().getContent());
+        }
+    },
+
+    /** A modifier signalling the following number is positive. */
+    MOD_POSITIVE(TokenTypeArity.UNARY, "\\+", 100, "NUMBER_*") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return token.getChildren().get(0).evaluate();
+        }
+    },
+
+    /** A modifier signalling the following number is negative. */
+    MOD_NEGATIVE(TokenTypeArity.UNARY, "-", 100, "NUMBER_*") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return -1 * token.getChildren().get(0).evaluate().floatValue();
+        }
+    },
+
+    /** The addition operator. */
+    OP_PLUS(TokenTypeArity.BINARY, "\\+", 7, "NUMBER_*", "BRACKET_OPEN") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return token.getChildren().get(0).evaluate().floatValue()
+                    + token.getChildren().get(1).evaluate().floatValue();
+        }
+    },
+
+    /** The subtraction operator. */
+    OP_MINUS(TokenTypeArity.BINARY, "-", 6, "NUMBER_*", "BRACKET_OPEN") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return token.getChildren().get(0).evaluate().floatValue()
+                    - token.getChildren().get(1).evaluate().floatValue();
+        }
+    },
+
+    /** The multiplication operator. */
+    OP_MULT(TokenTypeArity.BINARY, "(?=\\()|\\*", 9, "NUMBER_*", "BRACKET_OPEN") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return token.getChildren().get(0).evaluate().floatValue()
+                    * token.getChildren().get(1).evaluate().floatValue();
+        }
+    },
+
+    /** The division operator. */
+    OP_DIVIDE(TokenTypeArity.BINARY, "/", 10, "NUMBER_*", "BRACKET_OPEN") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return token.getChildren().get(0).evaluate().floatValue()
+                    / token.getChildren().get(1).evaluate().floatValue();
+        }
+    },
+
+    /** The modulo operator. */
+    OP_MOD(TokenTypeArity.BINARY, "%", 8, "NUMBER_*", "BRACKET_OPEN") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return token.getChildren().get(0).evaluate().floatValue()
+                    % token.getChildren().get(1).evaluate().floatValue();
+        }
+    },
+
+    /** The power operator. */
+    OP_POWER(TokenTypeArity.BINARY, "\\^", 11, "NUMBER_*", "BRACKET_OPEN") {
+        /** {@inheritDoc} */
+        @Override
+        public Number evaluate(final TreeToken token) {
+            return new Float(Math.pow(token.getChildren().get(0).evaluate().doubleValue(),
+                    token.getChildren().get(1).evaluate().doubleValue()));
+        }
+    },
+    ;
+
+    /** The string representation of tokens that may follow this one. */
+    private final String[] strfollows;
+    /** The precedence of this token. */
+    private final int precedence;
+    /** The list of tokens that may follow this one. */
+    private List<TokenType> follows;
+    /** The regular expression used to match this token. */
+    private final Pattern regex;
+    /** The arity of this token. */
+    private final TokenTypeArity arity;
+
+    /**
+     * Creates a new token type with the specified arguments.
+     *
+     * @param arity The arity of this token
+     * @param regex The regular expression used to match this token
+     * @param precedence The precendence of this token
+     * @param follows The names of the tokens which may follow this one
+     */
+    TokenType(final TokenTypeArity arity, final String regex,
+            final int precedence, final String ... follows) {
+        this.arity = arity;
+        this.strfollows = follows;
+        this.precedence = precedence;
+        this.regex = Pattern.compile(regex);
+    }
+
+    /**
+     * Retrieves a list of token types that may follow this one.
+     *
+     * @return A list of this token type's possible followers
+     */
+    public synchronized List<TokenType> getFollowers() {
+        if (follows == null) {
+            follows = new ArrayList<TokenType>();
+
+            for (int i = 0; i < strfollows.length; i++) {
+                follows.addAll(searchValueOf(strfollows[i]));
+            }
+        }
+
+        return follows;
+    }
+
+    /**
+     * Retrieves the arity of this token type.
+     *
+     * @return This token type's arity
+     */
+    public TokenTypeArity getArity() {
+        return arity;
+    }
+
+    /**
+     * Retrieves the precedence of this token type.
+     *
+     * @return This token type's precedence
+     */
+    public int getPrecedence() {
+        return precedence;
+    }
+
+    /**
+     * Attempts to match this token type against the specified input string
+     * (starting at the specified offset).
+     *
+     * @param input The string to be matched
+     * @param offset The offset within the string to start at
+     * @return -1 if no match was made, otherwise the number of characters that
+     * were matched as part of this token type.
+     */
+    public int match(final String input, final int offset) {
+        final Matcher matcher = regex.matcher(input);
+        matcher.useAnchoringBounds(false);
+        matcher.useTransparentBounds(true);
+
+        return matcher.find(offset) && matcher.start() == offset ? matcher.end() : -1;
+    }
+
+    /**
+     * Evaluates the specified token of this token type into a number.
+     *
+     * @param token The token to be evaluated
+     * @return A numerical representation of the specified token
+     */
+    public Number evaluate(final TreeToken token) {
+        throw new AbstractMethodError("Can't evaluate this token type");
+    }
+
+    /**
+     * Retrieves a list of types which match the specified name. The name
+     * may end with an asterisk (*), which is treated as a wild card.
+     *
+     * @param name The name to be searched for
+     * @return A list of matching tokens
+     */
+    protected static List<TokenType> searchValueOf(final String name) {
+        final List<TokenType> res = new ArrayList<TokenType>();
+
+        for (TokenType token : values()) {
+            if ((name.endsWith("*")
+                    && token.name().startsWith(name.substring(0, name.length() - 1)))
+                    || name.equals(token.name())) {
+                res.add(token);
+            }
+        }
+
+        return res;
+    }
+}

src/com/dmdirc/addons/calc/TokenTypeArity.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+/**
+ * Describes the arity (number of operands) of a token type.
+ *
+ * @author chris
+ */
+public enum TokenTypeArity {
+
+    /**
+     * A special type which does not have any operands and does not correspond
+     * to any input (e.g. the special START and END tokens).
+     */
+    HIDDEN,
+    /** A type which takes no operands. */
+    NULLARY,
+    /** A type which takes one operand. */
+    UNARY,
+    /** A type which takes two operands. */
+    BINARY;
+
+}

src/com/dmdirc/addons/calc/TreeToken.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Describes a tree of {@link Token}s.
+ * 
+ * @author chris
+ */
+public class TreeToken {
+
+    /** The children of this node. */
+    private final List<TreeToken> children = new ArrayList<TreeToken>();
+
+    /** The token at the root of the tree. */
+    private final Token token;
+
+    /** Whether or not this tree has been processed. */
+    private boolean processed = false;
+
+    /**
+     * Creates a new tree with the specified token at the root.
+     *
+     * @param token The root token
+     */
+    public TreeToken(final Token token) {
+        this.token = token;
+    }
+
+    /**
+     * Retrieves the (direct) children of this tree.
+     *
+     * @return This tree's children
+     */
+    public List<TreeToken> getChildren() {
+        return children;
+    }
+
+    /**
+     * Retrieves the root token of this tree.
+     *
+     * @return This tree's token
+     */
+    public Token getToken() {
+        return token;
+    }
+
+    /**
+     * Adds the specified child to this tree.
+     *
+     * @param token The child to be added
+     */
+    public void addChild(final TreeToken token) {
+        children.add(token);
+    }
+
+    /**
+     * Determines if this tree has been processed.
+     *
+     * @return True if the tree has been processed, false otherwise
+     */
+    public boolean isProcessed() {
+        return processed;
+    }
+
+    /**
+     * Sets the processed flag of this tree to true.
+     */
+    public void setProcessed() {
+        processed = true;
+    }
+
+    /**
+     * Evaluates this tree to return a number.
+     *
+     * @return A numerical evaluation of this tree.
+     */
+    public Number evaluate() {
+        return token.getType().evaluate(this);
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public String toString() {
+        return "[token: " + token + "; children: " + children + "; processed: "
+                + processed + "]";
+    }
+
+}

src/com/dmdirc/addons/calc/plugin.config

@@ -0,0 +1,25 @@
+# This is a DMDirc configuration file.
+
+# This section indicates which sections below take key/value
+# pairs, rather than a simple list. It should be placed above
+# any sections that take key/values.
+keysections:
+  metadata
+  updates
+  version
+
+metadata:
+  author=Chris <chris@dmdirc.com>
+  mainclass=com.dmdirc.addons.calc.CalcPlugin
+  description=Performs calculations
+  name=calc
+  nicename=Calc Plugin
+
+updates:
+  id=37
+
+version:
+  friendly=1.0
+
+provides:
+  calc command

test/com/dmdirc/addons/calc/EvaluatorTest.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import java.text.ParseException;
+import java.util.Arrays;
+import java.util.List;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import static org.junit.Assert.*;
+
+@RunWith(Parameterized.class)
+public class EvaluatorTest {
+
+    private final String input;
+    private final float output;
+
+    public EvaluatorTest(String input, String output) {
+        this.input = input;
+        this.output = Float.parseFloat(output);
+    }
+
+    @Test
+    public void testEvaluator() throws ParseException {
+        final Parser p = new Parser(new Lexer(input));
+        final Evaluator e = new Evaluator(p.parse());
+        assertEquals(output, e.evaluate().floatValue(), 0.01);
+    }
+
+    @Parameterized.Parameters
+    public static List<Object[]> data() {
+        final Object[][] data = {
+            {"1", "1"},
+            {"-1", "-1"},
+            {"1+1", "2"},
+            {"(1)", "1"},
+            {"(((1)))", "1"},
+            {"2(1*1)", "2"},
+            {"2+2*3/4-1", "2.5"},
+            {"1.0000(17.5+0.5)(1.000)", "18"},
+            {"2^3", "8"},
+        };
+
+        return Arrays.asList(data);
+    }
+
+    public static junit.framework.Test suite() {
+        return new junit.framework.JUnit4TestAdapter(EvaluatorTest.class);
+    }
+
+}

test/com/dmdirc/addons/calc/LexerTest.java

@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import java.text.ParseException;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class LexerTest {
+
+    @Test
+    public void testBasicNumber() throws ParseException {
+        final Lexer lexer = new Lexer("123");
+        final List<Token> tokens = lexer.tokenise();
+
+        assertEquals(3, tokens.size());
+        assertEquals(TokenType.START, tokens.get(0).getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(1).getType());
+        assertEquals("123", tokens.get(1).getContent());
+        assertEquals(TokenType.END, tokens.get(2).getType());
+    }
+
+    @Test
+    public void testComplexString() throws ParseException {
+        final Lexer lexer = new Lexer("(123 / 2.0) * ((3)+\t   (-1))");
+        final List<Token> tokens = lexer.tokenise();
+
+        System.out.println(Arrays.toString(tokens.toArray()));
+
+        assertEquals(18, tokens.size());
+        assertEquals(TokenType.START, tokens.get(0).getType());
+        assertEquals(TokenType.BRACKET_OPEN, tokens.get(1).getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(2).getType());
+        assertEquals("123", tokens.get(2).getContent());
+        assertEquals(TokenType.OP_DIVIDE, tokens.get(3).getType());
+        assertEquals(TokenType.NUMBER_FLOAT, tokens.get(4).getType());
+        assertEquals("2.0", tokens.get(4).getContent());
+        assertEquals(TokenType.BRACKET_CLOSE, tokens.get(5).getType());
+        assertEquals(TokenType.OP_MULT, tokens.get(6).getType());
+        assertEquals(TokenType.BRACKET_OPEN, tokens.get(7).getType());
+        assertEquals(TokenType.BRACKET_OPEN, tokens.get(8).getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(9).getType());
+        assertEquals("3", tokens.get(9).getContent());
+        assertEquals(TokenType.BRACKET_CLOSE, tokens.get(10).getType());
+        assertEquals(TokenType.OP_PLUS, tokens.get(11).getType());
+        assertEquals(TokenType.BRACKET_OPEN, tokens.get(12).getType());
+        assertEquals(TokenType.MOD_NEGATIVE, tokens.get(13).getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(14).getType());
+        assertEquals("1", tokens.get(14).getContent());
+        assertEquals(TokenType.BRACKET_CLOSE, tokens.get(15).getType());
+        assertEquals(TokenType.BRACKET_CLOSE, tokens.get(16).getType());
+        assertEquals(TokenType.END, tokens.get(17).getType());
+    }
+
+    @Test
+    public void testBrackets() throws ParseException {
+        final Lexer lexer = new Lexer("((1))");
+        final List<Token> tokens = lexer.tokenise();
+
+        assertEquals(7, tokens.size());
+        assertEquals(TokenType.START, tokens.get(0).getType());
+        assertEquals(TokenType.BRACKET_OPEN, tokens.get(1).getType());
+        assertEquals(TokenType.BRACKET_OPEN, tokens.get(2).getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(3).getType());
+        assertEquals(TokenType.BRACKET_CLOSE, tokens.get(4).getType());
+        assertEquals(TokenType.BRACKET_CLOSE, tokens.get(5).getType());
+        assertEquals(TokenType.END, tokens.get(6).getType());
+    }
+
+    @Test
+    public void testImplicitMult() throws ParseException {
+        final Lexer lexer = new Lexer("1(2)(3)");
+        final List<Token> tokens = lexer.tokenise();
+
+        assertEquals(11, tokens.size());
+        assertEquals(TokenType.START, tokens.get(0).getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(1).getType());
+        assertEquals(TokenType.OP_MULT, tokens.get(2).getType());
+        assertEquals(TokenType.BRACKET_OPEN, tokens.get(3).getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(4).getType());
+        assertEquals(TokenType.BRACKET_CLOSE, tokens.get(5).getType());
+        assertEquals(TokenType.OP_MULT, tokens.get(6).getType());
+        assertEquals(TokenType.BRACKET_OPEN, tokens.get(7).getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(8).getType());
+        assertEquals(TokenType.BRACKET_CLOSE, tokens.get(9).getType());
+        assertEquals(TokenType.END, tokens.get(10).getType());
+    }
+
+    private void doIllegalTest(final String input, final int offset) {
+        try {
+            fail(Arrays.toString(new Lexer(input).tokenise().toArray()));
+        } catch (ParseException ex) {
+            assertEquals(offset, ex.getErrorOffset());
+        }
+    }
+
+    @Test public void testIllegalEnd1() { doIllegalTest("", 0); }
+    @Test public void testIllegalEnd2() { doIllegalTest("3+", 2); }
+    @Test public void testIllegalEnd3() { doIllegalTest("(", 1); }
+    @Test public void testIllegalOp1() { doIllegalTest("1++2", 2); }
+    @Test public void testIllegalOp2() { doIllegalTest("*1", 0); }
+
+}

test/com/dmdirc/addons/calc/ParserTest.java

@@ -0,0 +1,186 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class ParserTest {
+
+    @Test
+    public void testTokenTypesByPrecedence() {
+        int last = Integer.MAX_VALUE;
+
+        for (TokenType type : Parser.TOKENS_BY_PRECEDENCE) {
+            assertTrue(type.getPrecedence() <= last);
+            last = type.getPrecedence();
+        }
+    }
+
+    @Test
+    public void testFindTokenType() {
+        final List<TreeToken> tokens = new ArrayList<TreeToken>();
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_CLOSE, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_CLOSE, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_OPEN, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_CLOSE, null)));
+        tokens.add(new TreeToken(new Token(TokenType.OP_DIVIDE, null)));
+
+        assertEquals(0, Parser.findTokenType(tokens, TokenType.BRACKET_CLOSE));
+        assertEquals(2, Parser.findTokenType(tokens, TokenType.BRACKET_OPEN));
+        assertEquals(4, Parser.findTokenType(tokens, TokenType.OP_DIVIDE));
+        assertEquals(-1, Parser.findTokenType(tokens, TokenType.OP_MULT));
+
+        tokens.get(0).setProcessed();
+        assertEquals(1, Parser.findTokenType(tokens, TokenType.BRACKET_CLOSE));
+    }
+
+    @Test
+    public void testParseBracket() throws ParseException {
+        final Parser parser = new Parser(null);
+
+        final List<TreeToken> tokens = new ArrayList<TreeToken>();
+        tokens.add(new TreeToken(new Token(TokenType.START, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_OPEN, null)));
+        tokens.add(new TreeToken(new Token(TokenType.NUMBER_INT, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_CLOSE, null)));
+        tokens.add(new TreeToken(new Token(TokenType.END, null)));
+
+        parser.parseBracket(tokens, 3);
+        assertEquals(3, tokens.size());
+        assertEquals(TokenType.START, tokens.get(0).getToken().getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(1).getToken().getType());
+        assertEquals(TokenType.END, tokens.get(2).getToken().getType());
+    }
+
+    @Test
+    public void testParseBracket2() throws ParseException {
+        final Parser parser = new Parser(null);
+
+        final List<TreeToken> tokens = new ArrayList<TreeToken>();
+        tokens.add(new TreeToken(new Token(TokenType.START, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_OPEN, null)));
+        tokens.add(new TreeToken(new Token(TokenType.NUMBER_INT, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_OPEN, null)));
+        tokens.add(new TreeToken(new Token(TokenType.NUMBER_INT, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_CLOSE, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_CLOSE, null)));
+        tokens.add(new TreeToken(new Token(TokenType.END, null)));
+
+        parser.parseBracket(tokens, 5);
+        assertEquals(6, tokens.size());
+        assertEquals(TokenType.START, tokens.get(0).getToken().getType());
+        assertEquals(TokenType.BRACKET_OPEN, tokens.get(1).getToken().getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(2).getToken().getType());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(3).getToken().getType());
+        assertEquals(TokenType.BRACKET_CLOSE, tokens.get(4).getToken().getType());
+        assertEquals(TokenType.END, tokens.get(5).getToken().getType());
+    }
+
+    @Test
+    public void testParseNumber() {
+        final Parser parser = new Parser(null);
+
+        final List<TreeToken> tokens = new ArrayList<TreeToken>();
+        tokens.add(new TreeToken(new Token(TokenType.START, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_OPEN, null)));
+        tokens.add(new TreeToken(new Token(TokenType.NUMBER_INT, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_CLOSE, null)));
+        tokens.add(new TreeToken(new Token(TokenType.END, null)));
+
+        parser.parseNumber(tokens, 2);
+        assertEquals(5, tokens.size());
+        assertTrue(tokens.get(2).isProcessed());
+    }
+
+    @Test
+    public void testParseHidden() {
+        final Parser parser = new Parser(null);
+
+        final List<TreeToken> tokens = new ArrayList<TreeToken>();
+        tokens.add(new TreeToken(new Token(TokenType.START, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_OPEN, null)));
+        tokens.add(new TreeToken(new Token(TokenType.NUMBER_INT, null)));
+        tokens.add(new TreeToken(new Token(TokenType.BRACKET_CLOSE, null)));
+        tokens.add(new TreeToken(new Token(TokenType.END, null)));
+
+        parser.parseHiddenOperator(tokens, 0);
+        assertEquals(4, tokens.size());
+        assertTrue(tokens.get(0).getToken().getType() == TokenType.BRACKET_OPEN);
+
+        parser.parseHiddenOperator(tokens, 3);
+        assertEquals(3, tokens.size());
+        assertTrue(tokens.get(2).getToken().getType() == TokenType.BRACKET_CLOSE);
+    }
+
+    @Test
+    public void testParseUnaryOps() {
+        final Parser parser = new Parser(null);
+
+        final List<TreeToken> tokens = new ArrayList<TreeToken>();
+        tokens.add(new TreeToken(new Token(TokenType.START, null)));
+        tokens.add(new TreeToken(new Token(TokenType.MOD_NEGATIVE, null)));
+        tokens.add(new TreeToken(new Token(TokenType.NUMBER_INT, null)));
+        tokens.add(new TreeToken(new Token(TokenType.END, null)));
+
+        parser.parseUnaryOperator(tokens, 1);
+        assertEquals(3, tokens.size());
+        assertTrue(tokens.get(0).getToken().getType() == TokenType.START);
+        assertTrue(tokens.get(1).getToken().getType() == TokenType.MOD_NEGATIVE);
+        assertTrue(tokens.get(2).getToken().getType() == TokenType.END);
+
+        assertTrue(tokens.get(1).isProcessed());
+        assertEquals(1, tokens.get(1).getChildren().size());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(1).getChildren().get(0).getToken().getType());
+    }
+
+    @Test
+    public void testParseBinaryOps() {
+        final Parser parser = new Parser(null);
+
+        final List<TreeToken> tokens = new ArrayList<TreeToken>();
+        tokens.add(new TreeToken(new Token(TokenType.START, null)));
+        tokens.add(new TreeToken(new Token(TokenType.NUMBER_INT, "15")));
+        tokens.add(new TreeToken(new Token(TokenType.OP_MINUS, null)));
+        tokens.add(new TreeToken(new Token(TokenType.NUMBER_INT, "10")));
+        tokens.add(new TreeToken(new Token(TokenType.END, null)));
+
+        parser.parseBinaryOperator(tokens, 2);
+
+        assertEquals(3, tokens.size());
+        assertTrue(tokens.get(0).getToken().getType() == TokenType.START);
+        assertTrue(tokens.get(1).getToken().getType() == TokenType.OP_MINUS);
+        assertTrue(tokens.get(2).getToken().getType() == TokenType.END);
+
+        assertTrue(tokens.get(1).isProcessed());
+        assertEquals(2, tokens.get(1).getChildren().size());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(1).getChildren().get(0).getToken().getType());
+        assertEquals("15", tokens.get(1).getChildren().get(0).getToken().getContent());
+        assertEquals(TokenType.NUMBER_INT, tokens.get(1).getChildren().get(1).getToken().getType());
+        assertEquals("10", tokens.get(1).getChildren().get(1).getToken().getContent());
+    }
+
+}

test/com/dmdirc/addons/calc/TokenTypeTest.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2006-2010 Chris Smith, Shane Mc Cormack, Gregory Holmes
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.dmdirc.addons.calc;
+
+import java.util.List;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class TokenTypeTest {
+
+    @Test
+    public void testSearchValueOf() {
+        List<TokenType> res = TokenType.searchValueOf("NUMBER_*");
+        assertEquals(2, res.size());
+        assertTrue(res.contains(TokenType.NUMBER_FLOAT));
+        assertTrue(res.contains(TokenType.NUMBER_INT));
+
+        res = TokenType.searchValueOf("START");
+        assertEquals(1, res.size());
+        assertTrue(res.contains(TokenType.START));
+    }
+
+    @Test
+    public void testMatch() {
+        assertEquals(0, TokenType.START.match("Foo", 0));
+        assertEquals(-1, TokenType.START.match("Foo", 1));
+        assertEquals(1, TokenType.NUMBER_INT.match("1+3", 0));
+        assertEquals(4, TokenType.NUMBER_INT.match("1234+3", 0));
+        assertEquals(3, TokenType.END.match("1+3", 3));
+        assertEquals(-1, TokenType.END.match("1+3", 2));
+    }
+
+    @Test
+    public void testGetFollowers() {
+        assertTrue(TokenType.END.getFollowers().isEmpty());
+        assertFalse(TokenType.START.getFollowers().isEmpty());
+    }
+
+}