lnav/src/pcrepp.hh

/**
 * Copyright (c) 2007-2013, Timothy Stack
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 * * 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.
 * * Neither the name of Timothy Stack nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''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 REGENTS OR CONTRIBUTORS 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.
 *
 * @file pcrepp.hh
 *
 * A C++ adapter for the pcre library.  The interface provided here has a
 * different focus than the pcrecpp.h file included in the pcre distribution.
 * The standard pcrecpp.h interface is more concerned with regular expressions
 * that are digesting data to be used within the program itself.  Whereas this
 * interface is dealing with regular expression entered by the user and
 * processing a series of matches on text files.
 */

#ifndef __pcrepp_hh
#define __pcrepp_hh

#ifdef HAVE_PCRE_H
#include <pcre.h>
#elif HAVE_PCRE_PCRE_H
#include <pcre/pcre.h>
#else
#error "pcre.h not found?"
#endif

#include <string.h>

#include <string>
#include <memory>
#include <exception>

#include "auto_mem.hh"

#include <stdio.h>

/**
 * Context that tracks captures found during a match operation.  This class is a
 * base that defines iterator methods and fields, but does not allocate space
 * for the capture array.
 */
class pcre_context {
public:
    typedef struct capture {
        capture() : c_begin(-1), c_end(-1) { };
        capture(int begin, int end) : c_begin(begin), c_end(end)
        {
            assert(begin <= end);
        };

        int c_begin;
        int c_end;

        int length() const { return this->c_end - this->c_begin; };
    } capture_t;
    typedef capture_t       *iterator;
    typedef const capture_t *const_iterator;

    /** @return The maximum number of strings this context can capture. */
    int get_max_count() const
    {
        return this->pc_max_count;
    };

    void set_count(int count)
    {
        this->pc_count = count;
    };

    int get_count(void) const
    {
        return this->pc_count;
    };

    /**
     * @return a capture_t that covers all of the text that was matched.
     */
    capture_t *all() { return pc_captures; };

    /** @return An iterator to the first capture. */
    iterator begin() { return pc_captures + 1; };
    /** @return An iterator that refers to the end of the capture array. */
    iterator end() { return pc_captures + pc_count; };

protected:
    pcre_context(capture_t *captures, int max_count)
        : pc_captures(captures), pc_max_count(max_count), pc_count(0) { };

    capture_t *pc_captures;
    int        pc_max_count;
    int        pc_count;
};

struct capture_if_not {
    capture_if_not(int begin) : cin_begin(begin) { };

    bool operator()(const pcre_context::capture_t &cap) const
    {
        return cap.c_begin != this->cin_begin;
    }

    int cin_begin;
};

inline
pcre_context::iterator skip_invalid_captures(pcre_context::iterator iter,
                                             pcre_context::iterator pc_end)
{
    for (; iter != pc_end; ++iter) {
        if (iter->c_begin == -1) {
            continue;
        }
    }

    return iter;
}

/**
 * A pcre_context that allocates storage for the capture array within the object
 * itself.
 */
template<size_t MAX_COUNT>
class pcre_context_static : public pcre_context {
public:
    pcre_context_static()
        : pcre_context(this->pc_match_buffer, MAX_COUNT + 1) { };

private:
    capture_t pc_match_buffer[MAX_COUNT + 1];
};

/**
 *
 */
class pcre_input {
public:
    pcre_input(const char *str, size_t off = 0, size_t len = -1)
        : pi_offset(off),
          pi_next_offset(off),
          pi_length(len),
          pi_string(str)
    {
        if (this->pi_length == (size_t)-1) {
            this->pi_length = strlen(str);
        }
    };

    pcre_input(const std::string &str, size_t off = 0)
        : pi_offset(off),
          pi_next_offset(off),
          pi_length(str.length()),
          pi_string(str.c_str()) {};

    const char *get_string() const { return this->pi_string; };

    const char *get_substr_start(const pcre_context::iterator iter) const
    {
        return &this->pi_string[iter->c_begin];
    };

    std::string get_substr(pcre_context::const_iterator iter) const
    {
        if (iter->c_begin == -1) {
            return "";
        }
        return std::string(this->pi_string,
                           iter->c_begin,
                           iter->length());
    };

    void reset(const char *str, size_t off = 0, size_t len = -1)
    {
        this->pi_string      = str;
        this->pi_offset      = off;
        this->pi_next_offset = off;
        if (this->pi_length == (size_t)-1) {
            this->pi_length = strlen(str);
        }
        else {
            this->pi_length = len;
        }
    }

    void reset(const std::string &str, size_t off = 0)
    {
        this->reset(str.c_str(), off, str.length());
    }

    size_t pi_offset;
    size_t pi_next_offset;
    size_t pi_length;
private:
    const char *pi_string;
};

class pcrepp {
public:
    class error : public std::exception {
public:
        error(std::string msg, int offset)
            : e_msg(msg), e_offset(offset) { };
        virtual ~error() throw () { };

        virtual const char *what() const throw()
        {
            return this->e_msg.c_str();
        };

        const std::string e_msg;
        int e_offset;
    };

    pcrepp(pcre *code) : p_code(code), p_code_extra(pcre_free_study)
    {
        pcre_refcount(this->p_code, 1);
        this->study();
    };

    pcrepp(const char *pattern, int options =
               0) : p_code_extra(pcre_free_study)
    {
        const char *errptr;
        int         eoff;

        if ((this->p_code = pcre_compile(pattern,
                                         options,
                                         &errptr,
                                         &eoff,
                                         NULL)) == NULL) {
            throw error(errptr, eoff);
        }

        pcre_refcount(this->p_code, 1);
        this->study();
    };

    pcrepp(const pcrepp &other)
    {
        this->p_code = other.p_code;
        pcre_refcount(this->p_code, 1);
        this->study();
    };

    virtual ~pcrepp()
    {
        if (pcre_refcount(this->p_code, -1) == 0) {
            free(this->p_code);
            this->p_code = 0;
        }
    };

    bool match(pcre_context &pc, pcre_input &pi, int options = 0) const
    {
        int         length, startoffset, filtered_options = options;
        int         count = pc.get_max_count();
        const char *str;
        int         rc;

        pi.pi_offset = pi.pi_next_offset;

        str = pi.get_string();
        if (filtered_options & PCRE_ANCHORED) {
            filtered_options &= ~PCRE_ANCHORED;
            str         = &str[pi.pi_offset];
            startoffset = 0;
            length      = pi.pi_length - pi.pi_offset;
        }
        else {
            startoffset = pi.pi_offset;
            length      = pi.pi_length;
        }
        rc = pcre_exec(this->p_code,
                       this->p_code_extra.in(),
                       str,
                       length,
                       startoffset,
                       filtered_options,
                       (int *)pc.all(),
                       count * 2);

        if (rc < 0) {
            switch (rc) {
            case PCRE_ERROR_NOMATCH:
                break;

            default:
                fprintf(stderr, "pcre err %d\n", rc);
                break;
            }
        }
        else if (rc == 0) {
            rc = 0;
        }
        else if (pc.all()->c_begin == pc.all()->c_end) {
            rc = 0;
        }
        else {
            if (options & PCRE_ANCHORED) {
                for (int lpc = 0; lpc < rc; lpc++) {
                    if (pc.all()[lpc].c_begin == -1) {
                        continue;
                    }
                    pc.all()[lpc].c_begin += pi.pi_offset;
                    pc.all()[lpc].c_end   += pi.pi_offset;
                }
            }
            pi.pi_next_offset = pc.all()->c_end;
        }

        pc.set_count(rc);

        return rc > 0;
    };

#ifdef PCRE_STUDY_JIT_COMPILE
    static pcre_jit_stack *jit_stack(void);

#else
    static void pcre_free_study(pcre_extra *);
#endif

private:

    void study(void)
    {
        const char *errptr;

        this->p_code_extra = pcre_study(this->p_code,
#ifdef PCRE_STUDY_JIT_COMPILE
                                        PCRE_STUDY_JIT_COMPILE,
#else
                                        0,
#endif
                                        &errptr);
        if (!this->p_code_extra && errptr) {
            fprintf(stderr, "pcre_study error: %s\n", errptr);
        }
        if (this->p_code_extra != NULL) {
            pcre_extra *extra = this->p_code_extra;

            extra->flags |= (PCRE_EXTRA_MATCH_LIMIT |
                             PCRE_EXTRA_MATCH_LIMIT_RECURSION);
            extra->match_limit           = 10000;
            extra->match_limit_recursion = 500;
#ifdef PCRE_STUDY_JIT_COMPILE
            pcre_assign_jit_stack(extra, NULL, jit_stack());
#endif
        }
    };

    pcre *p_code;
    auto_mem<pcre_extra> p_code_extra;
};
#endif