/*
[The "BSD licence"]
Copyright (c) 2005-2006 Terence Parr
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products
derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.antlr.codegen;

import org.antlr.Tool;
import org.antlr.stringtemplate.StringTemplate;
import org.antlr.tool.Grammar;

import java.io.IOException;
import java.util.ArrayList;

public class CTarget extends Target {

    ArrayList strings = new ArrayList();

    @Override
    protected void genRecognizerFile(Tool tool,
            CodeGenerator generator,
            Grammar grammar,
            StringTemplate outputFileST)
            throws IOException {

        // Before we write this, and cause it to generate its string,
        // we need to add all the string literals that we are going to match
        //
        outputFileST.setAttribute("literals", strings);
        String fileName = generator.getRecognizerFileName(grammar.name, grammar.type);
        generator.write(outputFileST, fileName);
    }

    @Override
    protected void genRecognizerHeaderFile(Tool tool,
            CodeGenerator generator,
            Grammar grammar,
            StringTemplate headerFileST,
            String extName)
            throws IOException {
        // Pick up the file name we are generating. This method will return a
        // a file suffixed with .c, so we must substring and add the extName
        // to it as we cannot assign into strings in Java.
        ///
        String fileName = generator.getRecognizerFileName(grammar.name, grammar.type);
        fileName = fileName.substring(0, fileName.length() - 2) + extName;

        generator.write(headerFileST, fileName);
    }

    protected StringTemplate chooseWhereCyclicDFAsGo(Tool tool,
            CodeGenerator generator,
            Grammar grammar,
            StringTemplate recognizerST,
            StringTemplate cyclicDFAST) {
        return recognizerST;
    }

    /** Is scope in @scope::name {action} valid for this kind of grammar?
     *  Targets like C++ may want to allow new scopes like headerfile or
     *  some such.  The action names themselves are not policed at the
     *  moment so targets can add template actions w/o having to recompile
     *  ANTLR.
     */
    @Override
    public boolean isValidActionScope(int grammarType, String scope) {
        switch (grammarType) {
            case Grammar.LEXER:
                if (scope.equals("lexer")) {
                    return true;
                }
                if (scope.equals("header")) {
                    return true;
                }
                if (scope.equals("includes")) {
                    return true;
                }
                if (scope.equals("preincludes")) {
                    return true;
                }
                if (scope.equals("overrides")) {
                    return true;
                }
                break;
            case Grammar.PARSER:
                if (scope.equals("parser")) {
                    return true;
                }
                if (scope.equals("header")) {
                    return true;
                }
                if (scope.equals("includes")) {
                    return true;
                }
                if (scope.equals("preincludes")) {
                    return true;
                }
                if (scope.equals("overrides")) {
                    return true;
                }
                break;
            case Grammar.COMBINED:
                if (scope.equals("parser")) {
                    return true;
                }
                if (scope.equals("lexer")) {
                    return true;
                }
                if (scope.equals("header")) {
                    return true;
                }
                if (scope.equals("includes")) {
                    return true;
                }
                if (scope.equals("preincludes")) {
                    return true;
                }
                if (scope.equals("overrides")) {
                    return true;
                }
                break;
            case Grammar.TREE_PARSER:
                if (scope.equals("treeparser")) {
                    return true;
                }
                if (scope.equals("header")) {
                    return true;
                }
                if (scope.equals("includes")) {
                    return true;
                }
                if (scope.equals("preincludes")) {
                    return true;
                }
                if (scope.equals("overrides")) {
                    return true;
                }
                break;
        }
        return false;
    }

    @Override
    public String getTargetCharLiteralFromANTLRCharLiteral(
            CodeGenerator generator,
            String literal) {

        if (literal.startsWith("'\\u")) {
            literal = "0x" + literal.substring(3, 7);
        } else {
            int c = literal.charAt(1);

            if (c < 32 || c > 127) {
                literal = "0x" + Integer.toHexString(c);
            }
        }

        return literal;
    }

    /** Convert from an ANTLR string literal found in a grammar file to
     *  an equivalent string literal in the C target.
     *  Because we must support Unicode character sets and have chosen
     *  to have the lexer match UTF32 characters, then we must encode
     *  string matches to use 32 bit character arrays. Here then we
     *  must produce the C array and cater for the case where the 
     *  lexer has been encoded with a string such as 'xyz\n',
     */
    @Override
    public String getTargetStringLiteralFromANTLRStringLiteral(
            CodeGenerator generator,
            String literal) {
        int index;
        String bytes;
        StringBuffer buf = new StringBuffer();

        buf.append("{ ");

        // We need ot lose any escaped characters of the form \x and just
        // replace them with their actual values as well as lose the surrounding
        // quote marks.
        //
        for (int i = 1; i < literal.length() - 1; i++) {
            buf.append("0x");

            if (literal.charAt(i) == '\\') {
                i++; // Assume that there is a next character, this will just yield
                // invalid strings if not, which is what the input would be of course - invalid
                switch (literal.charAt(i)) {
                    case 'u':
                    case 'U':
                        buf.append(literal.substring(i + 1, i + 5));  // Already a hex string
                        i = i + 5;                                // Move to next string/char/escape
                        break;

                    case 'n':
                    case 'N':

                        buf.append("0A");
                        break;

                    case 'r':
                    case 'R':

                        buf.append("0D");
                        break;

                    case 't':
                    case 'T':

                        buf.append("09");
                        break;

                    case 'b':
                    case 'B':

                        buf.append("08");
                        break;

                    case 'f':
                    case 'F':

                        buf.append("0C");
                        break;

                    default:

                        // Anything else is what it is!
                        //
                        buf.append(Integer.toHexString((int) literal.charAt(i)).toUpperCase());
                        break;
                }
            } else {
                buf.append(Integer.toHexString((int) literal.charAt(i)).toUpperCase());
            }
            buf.append(", ");
        }
        buf.append(" ANTLR3_STRING_TERMINATOR}");

        bytes = buf.toString();
        index = strings.indexOf(bytes);

        if (index == -1) {
            strings.add(bytes);
            index = strings.indexOf(bytes);
        }

        String strref = "lit_" + String.valueOf(index + 1);

        return strref;
    }

    /**
     * Overrides the standard grammar analysis so we can prepare the analyser
     * a little differently from the other targets.
     *
     * In particular we want to influence the way the code generator makes assumptions about
     * switchs vs ifs, vs table driven DFAs. In general, C code should be generated that
     * has the minimum use of tables, and tha meximum use of large switch statements. This
     * allows the optimizers to generate very efficient code, it can reduce object code size
     * by about 30% and give about a 20% performance improvement over not doing this. Hence,
     * for the C target only, we change the defaults here, but only if they are still set to the
     * defaults.
     *
     * @param generator An instance of the generic code generator class.
     * @param grammar The grammar that we are currently analyzing
     */
    @Override
    protected void performGrammarAnalysis(CodeGenerator generator, Grammar grammar) {

        // Check to see if the maximum inline DFA states is still set to
        // the default size. If it is then whack it all the way up to the maximum that
        // we can sensibly get away with.
        //
        if (CodeGenerator.MAX_ACYCLIC_DFA_STATES_INLINE == CodeGenerator.MADSI_DEFAULT) {

            CodeGenerator.MAX_ACYCLIC_DFA_STATES_INLINE = 65535;
        }

        // Check to see if the maximum switch size is still set to the default
        // and bring it up much higher if it is. Modern C compilers can handle
        // much bigger switch statements than say Java can and if anyone finds a compiler
        // that cannot deal with such big switches, all the need do is generate the
        // code with a reduced -Xmaxswitchcaselabels nnn
        //
        if  (CodeGenerator.MAX_SWITCH_CASE_LABELS == CodeGenerator.MSCL_DEFAULT) {

            CodeGenerator.MAX_SWITCH_CASE_LABELS = 3000;
        }

        // Check to see if the number of transitions considered a miminum for using
        // a switch is still at the default. Because a switch is still generally faster than
        // an if even with small sets, and given that the optimizer will do the best thing with it
        // anyway, then we simply want to generate a switch for any number of states.
        //
        if (CodeGenerator.MIN_SWITCH_ALTS == CodeGenerator.MSA_DEFAULT) {

            CodeGenerator.MIN_SWITCH_ALTS = 1;
        }

        // Now we allow the superclass implementation to do whatever it feels it
        // must do.
        //
        super.performGrammarAnalysis(generator, grammar);
    }
}

