C++ ini 实现

首先是从 https://github.com/benhoyt/inih 取用的 ini 读取类头文件

//file ini.h
/* inih -- simple .INI file parser

SPDX-License-Identifier: BSD-3-Clause

Copyright (C) 2009-2020, Ben Hoyt

inih is released under the New BSD license (see LICENSE.txt). Go to the project
home page for more info:

https://github.com/benhoyt/inih

*/

#ifndef INI_H
#define INI_H

/* Make this header file easier to include in C++ code */
#ifdef __cplusplus
extern "C" {
#endif

#include <stdio.h>

    /* Nonzero if ini_handler callback should accept lineno parameter. */
#ifndef INI_HANDLER_LINENO
#define INI_HANDLER_LINENO 0
#endif

/* Visibility symbols, required for Windows DLLs */
#ifndef INI_API
#if defined _WIN32 || defined __CYGWIN__
#	ifdef INI_SHARED_LIB
#		ifdef INI_SHARED_LIB_BUILDING
#			define INI_API __declspec(dllexport)
#		else
#			define INI_API __declspec(dllimport)
#		endif
#	else
#		define INI_API
#	endif
#else
#	if defined(__GNUC__) && __GNUC__ >= 4
#		define INI_API __attribute__ ((visibility ("default")))
#	else
#		define INI_API
#	endif
#endif
#endif

/* Typedef for prototype of handler function. */
#if INI_HANDLER_LINENO
    typedef int (*ini_handler)(void* user, const char* section,
        const char* name, const char* value,
        int lineno);
#else
    typedef int (*ini_handler)(void* user, const char* section,
        const char* name, const char* value);
#endif

    /* Typedef for prototype of fgets-style reader function. */
    typedef char* (*ini_reader)(char* str, int num, void* stream);

    /* Parse given INI-style file. May have [section]s, name=value pairs
       (whitespace stripped), and comments starting with ';' (semicolon). Section
       is "" if name=value pair parsed before any section heading. name:value
       pairs are also supported as a concession to Python's configparser.

       For each name=value pair parsed, call handler function with given user
       pointer as well as section, name, and value (data only valid for duration
       of handler call). Handler should return nonzero on success, zero on error.

       Returns 0 on success, line number of first error on parse error (doesn't
       stop on first error), -1 on file open error, or -2 on memory allocation
       error (only when INI_USE_STACK is zero).
    */
    INI_API int ini_parse(const char* filename, ini_handler handler, void* user);

    /* Same as ini_parse(), but takes a FILE* instead of filename. This doesn't
       close the file when it's finished -- the caller must do that. */
    INI_API int ini_parse_file(FILE* file, ini_handler handler, void* user);

    /* Same as ini_parse(), but takes an ini_reader function pointer instead of
       filename. Used for implementing custom or string-based I/O (see also
       ini_parse_string). */
    INI_API int ini_parse_stream(ini_reader reader, void* stream, ini_handler handler,
        void* user);

    /* Same as ini_parse(), but takes a zero-terminated string with the INI data
    instead of a file. Useful for parsing INI data from a network socket or
    already in memory. */
    INI_API int ini_parse_string(const char* string, ini_handler handler, void* user);

    /* Nonzero to allow multi-line value parsing, in the style of Python's
       configparser. If allowed, ini_parse() will call the handler with the same
       name for each subsequent line parsed. */
#ifndef INI_ALLOW_MULTILINE
#define INI_ALLOW_MULTILINE 1
#endif

       /* Nonzero to allow a UTF-8 BOM sequence (0xEF 0xBB 0xBF) at the start of
          the file. See https://github.com/benhoyt/inih/issues/21 */
#ifndef INI_ALLOW_BOM
#define INI_ALLOW_BOM 1
#endif

          /* Chars that begin a start-of-line comment. Per Python configparser, allow
             both ; and # comments at the start of a line by default. */
#ifndef INI_START_COMMENT_PREFIXES
#define INI_START_COMMENT_PREFIXES ";#"
#endif

             /* Nonzero to allow inline comments (with valid inline comment characters
                specified by INI_INLINE_COMMENT_PREFIXES). Set to 0 to turn off and match
                Python 3.2+ configparser behaviour. */
#ifndef INI_ALLOW_INLINE_COMMENTS
#define INI_ALLOW_INLINE_COMMENTS 1
#endif
#ifndef INI_INLINE_COMMENT_PREFIXES
#define INI_INLINE_COMMENT_PREFIXES ";"
#endif

                /* Nonzero to use stack for line buffer, zero to use heap (malloc/free). */
#ifndef INI_USE_STACK
#define INI_USE_STACK 1
#endif

/* Maximum line length for any line in INI file (stack or heap). Note that
   this must be 3 more than the longest line (due to '\r', '\n', and '\0'). */
#ifndef INI_MAX_LINE
#define INI_MAX_LINE 200
#endif

   /* Nonzero to allow heap line buffer to grow via realloc(), zero for a
      fixed-size buffer of INI_MAX_LINE bytes. Only applies if INI_USE_STACK is
      zero. */
#ifndef INI_ALLOW_REALLOC
#define INI_ALLOW_REALLOC 0
#endif

      /* Initial size in bytes for heap line buffer. Only applies if INI_USE_STACK
         is zero. */
#ifndef INI_INITIAL_ALLOC
#define INI_INITIAL_ALLOC 200
#endif

         /* Stop parsing on first error (default is to keep parsing). */
#ifndef INI_STOP_ON_FIRST_ERROR
#define INI_STOP_ON_FIRST_ERROR 0
#endif

/* Nonzero to call the handler at the start of each new section (with
   name and value NULL). Default is to only call the handler on
   each name=value pair. */
#ifndef INI_CALL_HANDLER_ON_NEW_SECTION
#define INI_CALL_HANDLER_ON_NEW_SECTION 0
#endif

   /* Nonzero to allow a name without a value (no '=' or ':' on the line) and
      call the handler with value NULL in this case. Default is to treat
      no-value lines as an error. */
#ifndef INI_ALLOW_NO_VALUE
#define INI_ALLOW_NO_VALUE 0
#endif

      /* Nonzero to use custom ini_malloc, ini_free, and ini_realloc memory
         allocation functions (INI_USE_STACK must also be 0). These functions must
         have the same signatures as malloc/free/realloc and behave in a similar
         way. ini_realloc is only needed if INI_ALLOW_REALLOC is set. */
#ifndef INI_CUSTOM_ALLOCATOR
#define INI_CUSTOM_ALLOCATOR 0
#endif


#ifdef __cplusplus
}
#endif

#endif /* INI_H */

和对应的 ini 读取实现

//file ini.c
/* inih -- simple .INI file parser

SPDX-License-Identifier: BSD-3-Clause

Copyright (C) 2009-2020, Ben Hoyt

inih is released under the New BSD license (see LICENSE.txt). Go to the project
home page for more info:

https://github.com/benhoyt/inih

*/

#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
#define _CRT_SECURE_NO_WARNINGS
#endif

#include <stdio.h>
#include <ctype.h>
#include <string.h>

#include "ini.h"

#if !INI_USE_STACK
#if INI_CUSTOM_ALLOCATOR
#include <stddef.h>
void* ini_malloc(size_t size);
void ini_free(void* ptr);
void* ini_realloc(void* ptr, size_t size);
#else
#include <stdlib.h>
#define ini_malloc malloc
#define ini_free free
#define ini_realloc realloc
#endif
#endif

#define MAX_SECTION 50
#define MAX_NAME 50

/* Used by ini_parse_string() to keep track of string parsing state. */
typedef struct {
    const char* ptr;
    size_t num_left;
} ini_parse_string_ctx;

/* Strip whitespace chars off end of given string, in place. Return s. */
static char* rstrip(char* s)
{
    char* p = s + strlen(s);
    while (p > s && isspace((unsigned char)(*--p)))
        *p = '\0';
    return s;
}

/* Return pointer to first non-whitespace char in given string. */
static char* lskip(const char* s)
{
    while (*s && isspace((unsigned char)(*s)))
        s++;
    return (char*)s;
}

/* Return pointer to first char (of chars) or inline comment in given string,
   or pointer to NUL at end of string if neither found. Inline comment must
   be prefixed by a whitespace character to register as a comment. */
static char* find_chars_or_comment(const char* s, const char* chars)
{
#if INI_ALLOW_INLINE_COMMENTS
    int was_space = 0;
    while (*s && (!chars || !strchr(chars, *s)) &&
        !(was_space && strchr(INI_INLINE_COMMENT_PREFIXES, *s))) {
        was_space = isspace((unsigned char)(*s));
        s++;
    }
#else
    while (*s && (!chars || !strchr(chars, *s))) {
        s++;
    }
#endif
    return (char*)s;
}

/* Similar to strncpy, but ensures dest (size bytes) is
   NUL-terminated, and doesn't pad with NULs. */
static char* strncpy0(char* dest, const char* src, size_t size)
{
    /* Could use strncpy internally, but it causes gcc warnings (see issue #91) */
    size_t i;
    for (i = 0; i < size - 1 && src[i]; i++)
        dest[i] = src[i];
    dest[i] = '\0';
    return dest;
}

/* See documentation in header file. */
int ini_parse_stream(ini_reader reader, void* stream, ini_handler handler,
    void* user)
{
    /* Uses a fair bit of stack (use heap instead if you need to) */
#if INI_USE_STACK
    char line[INI_MAX_LINE];
    size_t max_line = INI_MAX_LINE;
#else
    char* line;
    size_t max_line = INI_INITIAL_ALLOC;
#endif
#if INI_ALLOW_REALLOC && !INI_USE_STACK
    char* new_line;
    size_t offset;
#endif
    char section[MAX_SECTION] = "";
    char prev_name[MAX_NAME] = "";

    char* start;
    char* end;
    char* name;
    char* value;
    int lineno = 0;
    int error = 0;

#if !INI_USE_STACK
    line = (char*)ini_malloc(INI_INITIAL_ALLOC);
    if (!line) {
        return -2;
    }
#endif

#if INI_HANDLER_LINENO
#define HANDLER(u, s, n, v) handler(u, s, n, v, lineno)
#else
#define HANDLER(u, s, n, v) handler(u, s, n, v)
#endif

    /* Scan through stream line by line */
    while (reader(line, (int)max_line, stream) != NULL) {
#if INI_ALLOW_REALLOC && !INI_USE_STACK
        offset = strlen(line);
        while (offset == max_line - 1 && line[offset - 1] != '\n') {
            max_line *= 2;
            if (max_line > INI_MAX_LINE)
                max_line = INI_MAX_LINE;
            new_line = ini_realloc(line, max_line);
            if (!new_line) {
                ini_free(line);
                return -2;
            }
            line = new_line;
            if (reader(line + offset, (int)(max_line - offset), stream) == NULL)
                break;
            if (max_line >= INI_MAX_LINE)
                break;
            offset += strlen(line + offset);
        }
#endif

        lineno++;

        start = line;
#if INI_ALLOW_BOM
        if (lineno == 1 && (unsigned char)start[0] == 0xEF &&
            (unsigned char)start[1] == 0xBB &&
            (unsigned char)start[2] == 0xBF) {
            start += 3;
        }
#endif
        start = lskip(rstrip(start));

        if (strchr(INI_START_COMMENT_PREFIXES, *start)) {
            /* Start-of-line comment */
        }
#if INI_ALLOW_MULTILINE
        else if (*prev_name && *start && start > line) {
#if INI_ALLOW_INLINE_COMMENTS
            end = find_chars_or_comment(start, NULL);
            if (*end)
                *end = '\0';
            rstrip(start);
#endif
            /* Non-blank line with leading whitespace, treat as continuation
               of previous name's value (as per Python configparser). */
            if (!HANDLER(user, section, prev_name, start) && !error)
                error = lineno;
        }
#endif
        else if (*start == '[') {
            /* A "[section]" line */
            end = find_chars_or_comment(start + 1, "]");
            if (*end == ']') {
                *end = '\0';
                strncpy0(section, start + 1, sizeof(section));
                *prev_name = '\0';
#if INI_CALL_HANDLER_ON_NEW_SECTION
                if (!HANDLER(user, section, NULL, NULL) && !error)
                    error = lineno;
#endif
            }
            else if (!error) {
                /* No ']' found on section line */
                error = lineno;
            }
        }
        else if (*start) {
            /* Not a comment, must be a name[=:]value pair */
            end = find_chars_or_comment(start, "=:");
            if (*end == '=' || *end == ':') {
                *end = '\0';
                name = rstrip(start);
                value = end + 1;
#if INI_ALLOW_INLINE_COMMENTS
                end = find_chars_or_comment(value, NULL);
                if (*end)
                    *end = '\0';
#endif
                value = lskip(value);
                rstrip(value);

                /* Valid name[=:]value pair found, call handler */
                strncpy0(prev_name, name, sizeof(prev_name));
                if (!HANDLER(user, section, name, value) && !error)
                    error = lineno;
            }
            else if (!error) {
                /* No '=' or ':' found on name[=:]value line */
#if INI_ALLOW_NO_VALUE
                * end = '\0';
                name = rstrip(start);
                if (!HANDLER(user, section, name, NULL) && !error)
                    error = lineno;
#else
                error = lineno;
#endif
            }
        }

#if INI_STOP_ON_FIRST_ERROR
        if (error)
            break;
#endif
    }

#if !INI_USE_STACK
    ini_free(line);
#endif

    return error;
}

/* See documentation in header file. */
int ini_parse_file(FILE* file, ini_handler handler, void* user)
{
    return ini_parse_stream((ini_reader)fgets, file, handler, user);
}

/* See documentation in header file. */
int ini_parse(const char* filename, ini_handler handler, void* user)
{
    FILE* file;
    int error;

    file = fopen(filename, "r");
    if (!file)
        return -1;
    error = ini_parse_file(file, handler, user);
    fclose(file);
    return error;
}

/* An ini_reader function to read the next line from a string buffer. This
   is the fgets() equivalent used by ini_parse_string(). */
static char* ini_reader_string(char* str, int num, void* stream) {
    ini_parse_string_ctx* ctx = (ini_parse_string_ctx*)stream;
    const char* ctx_ptr = ctx->ptr;
    size_t ctx_num_left = ctx->num_left;
    char* strp = str;
    char c;

    if (ctx_num_left == 0 || num < 2)
        return NULL;

    while (num > 1 && ctx_num_left != 0) {
        c = *ctx_ptr++;
        ctx_num_left--;
        *strp++ = c;
        if (c == '\n')
            break;
        num--;
    }

    *strp = '\0';
    ctx->ptr = ctx_ptr;
    ctx->num_left = ctx_num_left;
    return str;
}

/* See documentation in header file. */
int ini_parse_string(const char* string, ini_handler handler, void* user) {
    ini_parse_string_ctx ctx;

    ctx.ptr = string;
    ctx.num_left = strlen(string);
    return ini_parse_stream((ini_reader)ini_reader_string, &ctx, handler,
        user);
}

用CPP封装一下

//file IniParser.h
#pragma once
#include<unordered_map>
#include<string>
#include<iostream>
#include<vector>
static std::string __EMPTY_STRING = "";
class IniParser
{
public:
    IniParser(const char* inifile);
    ~IniParser();
    std::string GetString(const std::string& section, const std::string& key, const std::string& def = __EMPTY_STRING);
    double GetDouble(const std::string& section, const std::string& key, double def);
    bool GetBoolean(const std::string& section, const std::string& key, bool def);
    std::vector<std::string> GetSections();
    std::vector<std::string> GetKeysOfSection(const std::string& section);
    friend int iniHandler(void* user, const char* section, const char* name, const char* value);
    friend std::ostream& operator<<(std::ostream& out, const IniParser& obj);
private:
    void addNewRecord(const char* section, const char* key, const char* value);

    std::unordered_map<std::string, std::unordered_map<std::string, std::string>> mCaches;
};

加上对应的实现

#include "IniParser.h"
#include "ini.h"
#include <stdlib.h>
#include <string.h>

static int iniHandler(void* user, const char* section, const char* name, const char* value)
{
    IniParser* parser = (IniParser*)(user);
    parser->addNewRecord(section, name, value);
    return 1;
}

std::ostream& operator<<(std::ostream& out, const IniParser& obj)
{
    for (auto& sec : obj.mCaches)
    {
        out << "[" << sec.first << "]\n";
        for (auto& keyValue : sec.second)
        {
            out << keyValue.first << " = " << keyValue.second << "\n";
        }
    }
    out << std::flush;
    return out;
}

IniParser::IniParser(const char* inifile)
{
    int ret = ini_parse(inifile, iniHandler, this);
}

IniParser::~IniParser()
{
}

std::string IniParser::GetString(const std::string& section, const std::string& key, const std::string& def)
{
    auto sec = mCaches.find(section);
    if (sec != mCaches.end())
    {
        auto keyValue = sec->second.find(key);
        if (keyValue != sec->second.end())
        {
            return keyValue->second;
        }
    }
    return def;
}

double IniParser::GetDouble(const std::string& section, const std::string& key, double def)
{
    auto ret = GetString(section, key);
    if (ret.empty())
    {
        return def;
    }
    try {
        double result = std::stod(ret);
        return result;
    }
    catch (std::exception& e) {
        return def;
    }
}

bool IniParser::GetBoolean(const std::string& section, const std::string& key, bool def)
{
    auto ret = GetString(section, key);
    if (ret.empty())
    {
        return def;
    }
    char firstChar = ret.at(0);
    return firstChar == 'T' || firstChar == 'Y' || firstChar == 'y' || firstChar == '1' || firstChar == 't';
}

std::vector<std::string> IniParser::GetSections()
{
    std::vector<std::string> ret;
    for (auto& sec : mCaches)
    {
        ret.emplace_back(sec.first);
    }
    return ret;
}

std::vector<std::string> IniParser::GetKeysOfSection(const std::string& section)
{
    std::vector<std::string> ret;
    auto sec = mCaches.find(section);
    if (sec != mCaches.end())
    {
        for (auto& keyValues : sec->second)
        {
            ret.emplace_back(keyValues.first);
        }
    }
    return ret;
}

void IniParser::addNewRecord(const char* section, const char* key, const char* value)
{
    if (section == nullptr || key == nullptr || value == nullptr) 
    {
        return;
    }
#define EMPTY(s) (strlen(s) == 0)
    if (EMPTY(section) || EMPTY(key) || EMPTY(value)) {
        return;
    }
    auto sec = mCaches.find(section);
    if (sec == mCaches.end())
    {
        std::unordered_map<std::string, std::string> tmpMap;
        tmpMap.emplace(key, value);
        mCaches.emplace(section, std::move(tmpMap));
    }
    else
    {
        auto ret = sec->second.try_emplace(key, value);
        if (!ret.second)
        {
            sec->second[key] = value;
        }
    }
}