re.java

java写的crawler

                case OP_BRANCH:
                {
                    // Check for choices
                    if (instruction[next + offsetOpcode] != OP_BRANCH)
                    {
                        // If there aren't any other choices, just evaluate this branch.
                        node += nodeSize;
                        continue;
                    }

                    // Try all available branches
                    short nextBranch;
                    do
                    {
                        // Try matching the branch against the string
                        if ((idxNew = matchNodes(node + nodeSize, maxNode, idx)) != -1)
                        {
                            return idxNew;
                        }
                        
                        // Go to next branch (if any)
                        nextBranch = (short)instruction[node + offsetNext];
                        node += nextBranch;
                    }
                    while (nextBranch != 0 && (instruction[node + offsetOpcode] == OP_BRANCH));

                    // Failed to match any branch!
                    return -1;
                }

                case OP_NOTHING:
                case OP_GOTO:

                    // Just advance to the next node without doing anything
                    break;

                case OP_END:

                    // Match has succeeded!
                    setParenEnd(0, idx);
                    return idx;

                default:

                    // Corrupt program
                    internalError("Invalid opcode '" + opcode + "'");
            }

            // Advance to the next node in the program
            node = next;
        }

        // We "should" never end up here
        internalError("Corrupt program");
        return -1;
    }

    /**
     * Match the current regular expression program against the current
     * input string, starting at index i of the input string.  This method
     * is only meant for internal use.
     * @param i The input string index to start matching at
     * @return True if the input matched the expression
     */
    protected boolean matchAt(int i)
    {
        // Initialize start pointer, paren cache and paren count
        start0 = -1;
        end0   = -1;
        start1 = -1;
        end1   = -1;
        start2 = -1;
        end2   = -1;
        startn = null;
        endn   = null;
        parenCount = 1;
        setParenStart(0, i);

        // Allocate backref arrays (unless optimizations indicate otherwise)
        if ((program.flags & REProgram.OPT_HASBACKREFS) != 0)
        {
            startBackref = new int[maxParen];
            endBackref = new int[maxParen];
        }

        // Match against string
        int idx;
        if ((idx = matchNodes(0, maxNode, i)) != -1)
        {
            setParenEnd(0, idx);
            return true;
        }

        // Didn't match
        parenCount = 0;
        return false;
    }

    /**
     * Matches the current regular expression program against a character array,
     * starting at a given index.
     * @param search String to match against
     * @param i Index to start searching at
     * @return True if string matched
     */
    public boolean match(String search, int i) 
    {
        return match(new StringCharacterIterator(search), i);
    }

    /**
     * Matches the current regular expression program against a character array,
     * starting at a given index.
     * @param search String to match against
     * @param i Index to start searching at
     * @return True if string matched
     */
    public boolean match(CharacterIterator search, int i)
    {
        // There is no compiled program to search with!
        if (program == null)
        {
            // This should be uncommon enough to be an error case rather
            // than an exception (which would have to be handled everywhere)
            internalError("No RE program to run!");
        }

        // Save string to search
        this.search = search;

        // Can we optimize the search by looking for a prefix string?
        if (program.prefix == null)
        {
            // Unprefixed matching must try for a match at each character
            for ( ;! search.isEnd(i - 1); i++)
            {
                // Try a match at index i
                if (matchAt(i))
                {
                    return true;
                }
            }
            return false;
        }
        else
        {
            // Prefix-anchored matching is possible
            boolean caseIndependent = (matchFlags & MATCH_CASEINDEPENDENT) != 0;
            char[] prefix = program.prefix;
            for ( ;! search.isEnd(i + prefix.length - 1); i++)
            {
                // If the first character of the prefix matches
                boolean match = false;
                if (caseIndependent)
                    match = Character.toLowerCase(search.charAt(i)) == Character.toLowerCase(prefix[0]);
                else
                    match = search.charAt(i) == prefix[0];
                if (match)
                {
                    // Save first character position
                    int firstChar = i++;
                    int k;
                    for (k = 1; k < prefix.length; )
                    {
                        // If there's a mismatch of any character in the prefix, give up
                        if (caseIndependent)
                            match = Character.toLowerCase(search.charAt(i++)) == Character.toLowerCase(prefix[k++]);
                        else
                            match = search.charAt(i++) == prefix[k++];
                        if (!match)
                        {
                            break;
                        }
                    }

                    // See if the whole prefix string matched
                    if (k == prefix.length)
                    {
                        // We matched the full prefix at firstChar, so try it
                        if (matchAt(firstChar))
                        {
                            return true;
                        }
                    }

                    // Match failed, reset i to continue the search
                    i = firstChar;
                }
            }
            return false;
        }
    }

    /**
     * Matches the current regular expression program against a String.
     * @param search String to match against
     * @return True if string matched
     */
    public boolean match(String search)
    {
        return match(search, 0);
    }

    /**
     * Splits a string into an array of strings on regular expression boundaries.
     * This function works the same way as the Perl function of the same name.
     * Given a regular expression of "[ab]+" and a string to split of
     * "xyzzyababbayyzabbbab123", the result would be the array of Strings
     * "[xyzzy, yyz, 123]".
     * @param s String to split on this regular exression
     * @return Array of strings
     */
    public String[] split(String s)
    {
        // Create new vector
        Vector v = new Vector();

        // Start at position 0 and search the whole string
        int pos = 0;
        int len = s.length();

        // Try a match at each position
        while (pos < len && match(s, pos))
        {
            // Get start of match
            int start = getParenStart(0);

            // Get end of match
            int newpos = getParenEnd(0);

            // Check if no progress was made
            if (newpos == pos)
            {
                v.addElement(s.substring(pos, start + 1));
                newpos++;
            }
            else
            {
                v.addElement(s.substring(pos, start));
            }

            // Move to new position
            pos = newpos;
        }

        // Push remainder if it's not empty
        String remainder = s.substring(pos);
        if (remainder.length() != 0)
        {
            v.addElement(remainder);
        }

        // Return vector as an array of strings
        String[] ret = new String[v.size()];
        v.copyInto(ret);
        return ret;
    }

    /**
     * Flag bit that indicates that subst should replace all occurrences of this
     * regular expression.
     */
    public static final int REPLACE_ALL          = 0x0000;

    /**
     * Flag bit that indicates that subst should only replace the first occurrence
     * of this regular expression.
     */
    public static final int REPLACE_FIRSTONLY    = 0x0001;

    /**
     * Substitutes a string for this regular expression in another string.
     * This method works like the Perl function of the same name.
     * Given a regular expression of "a*b", a String to substituteIn of
     * "aaaabfooaaabgarplyaaabwackyb" and the substitution String "-", the
     * resulting String returned by subst would be "-foo-garply-wacky-".
     * @param substituteIn String to substitute within
     * @param substitution String to substitute for all matches of this regular expression.
     * @return The string substituteIn with zero or more occurrences of the current
     * regular expression replaced with the substitution String (if this regular
     * expression object doesn't match at any position, the original String is returned
     * unchanged).
     */
    public String subst(String substituteIn, String substitution)
    {
        return subst(substituteIn, substitution, REPLACE_ALL);
    }

    /**
     * Substitutes a string for this regular expression in another string.
     * This method works like the Perl function of the same name.
     * Given a regular expression of "a*b", a String to substituteIn of
     * "aaaabfooaaabgarplyaaabwackyb" and the substitution String "-", the
     * resulting String returned by subst would be "-foo-garply-wacky-".
     * @param substituteIn String to substitute within
     * @param substitution String to substitute for matches of this regular expression
     * @param flags One or more bitwise flags from REPLACE_*.  If the REPLACE_FIRSTONLY
     * flag bit is set, only the first occurrence of this regular expression is replaced.
     * If the bit is not set (REPLACE_ALL), all occurrences of this pattern will be
     * replaced.
     * @return The string substituteIn with zero or more occurrences of the current
     * regular expression replaced with the substitution String (if this regular
     * expression object doesn't match at any position, the original String is returned
     * unchanged).
     */
    public String subst(String substituteIn, String substitution, int flags)
    {
        // String to return
        StringBuffer ret = new StringBuffer();

        // Start at position 0 and search the whole string
        int pos = 0;
        int len = substituteIn.length();

        // Try a match at each position
        while (pos < len && match(substituteIn, pos))
        {
            // Append string before match
            ret.append(substituteIn.substring(pos, getParenStart(0)));

            // Append substitution
            ret.append(substitution);

            // Move forward, skipping past match
            int newpos = getParenEnd(0);

            // We always want to make progress! 
            if (newpos == pos)
            {
                newpos++;
            }

            // Try new position
            pos = newpos;

            // Break out if we're only supposed to replace one