状态机学习（三）解析JSON1

来自

从零开始的 JSON 库教程

从零开始教授如何写一个符合标准的 C 语言 JSON 库

https://zhuanlan.zhihu.com/json-tutorial

根据第一课教程自己重新编写做了一点修改加深学习印象

//JsonParse.h
#pragma once
#include "JsonStruct.h"
#include <assert.h>
 
void DEFParseWhitespace(MyJsonStruct& js)
{
    while (js.jsonStr[js.index] == ' ' ||
        js.jsonStr[js.index] == '\r' ||
        js.jsonStr[js.index] == '\n') {
        js.index++;
    }
}
 
DefParseResult DEFParseNull(MyJsonStruct& js)
{
    assert(js.jsonStr[js.index] = 'n');
    if (js.jsonStr[js.index + 1] != 'u' ||
        js.jsonStr[js.index+2] != 'l' ||
        js.jsonStr[js.index+3] != 'l') {
        return DEF_PARSE_INVALID_VALUE;
    }
    js.index += 4;
    js.type = DEF_NULL;
    return DEF_PARSE_OK;
}
 
DefParseResult DEFParseValue(MyJsonStruct& js)
{
    switch (js.jsonStr[js.index]){
    case 'n':return DEFParseNull(js);
    case '\0':return DEF_PARSE_EXPECT_VALUE;
    default:return DEF_PARSE_INVALID_VALUE;
    }
}
 
 
DefParseType GetParseType(MyJsonStruct& js)
{
    return js.type;
}
 
 
void ResetJsonStruct(const char* jsonBuf, MyJsonStruct& js)
{
    js.jsonStr = jsonBuf;
    js.index = 0;
    js.type = DEF_NONE;
}
 
 
MyJsonStruct InitJsonStruct(char* jsonBuf)
{
    MyJsonStruct jsonStruct;
    ResetJsonStruct(jsonBuf, jsonStruct);
    return jsonStruct;
}
 
 
DefParseResult DEFParse(MyJsonStruct& jsonStruct)
{
    DefParseResult ret;
 
    DEFParseWhitespace(jsonStruct);
 
    if ((ret = DEFParseValue(jsonStruct)) == DEF_PARSE_OK) {
        DEFParseWhitespace(jsonStruct);
        if (jsonStruct.index < jsonStruct.jsonStr.size()) {
            ret = DEF_PARSE_ROOT_NOT_SINGULAR;
            jsonStruct.type = DEF_NONE;
        }
             
    }
    return ret;
}

//JsonStruct.h
#pragma once
#include <string>
 
enum DefParseType {
    DEF_NONE,
    DEF_NULL,
    DEF_FALSE,
    DEF_TRUE,
    DEF_NUMBER,
    DEF_STRING,
    DEF_ARRAY,
    DEF_OBJECT
};
 
struct MyJsonStruct {
    std::string jsonStr;
    size_t index;
    DefParseType type;
};
 
enum DefParseResult{
    DEF_PARSE_OK = 0,
    DEF_PARSE_EXPECT_VALUE,
    DEF_PARSE_INVALID_VALUE,
    DEF_PARSE_ROOT_NOT_SINGULAR
};

//MyTestUnit.h
#pragma once
#include <iostream>
 
 
class MyTestClass {
    static size_t testCount_;
    static size_t testPass_;
public:
    template<typename E,typename A>
    bool ExceptEqual(E e, A a)
    {
        testCount_++;
        if (e == a){
            testPass_++;
            return true;
        }
        return false;
    }
 
    void PrintResult(){
        std::cout << testPass_ << "/" << testCount_ << "\t" << "("<<(testPass_ * 100.0 / testCount_) << "%)" << " passed." << std::endl;
    }
};
size_t MyTestClass::testCount_ = 0;
size_t MyTestClass::testPass_ = 0;
 
#define ERROR_PRINT(expect,actual)                  \
 std::cerr << __FILE__ <<":"<< __LINE__ << "\r\nexpect: " << expect << "  actual: " << actual << std::endl; 
 
#define EXCEPT_EQ(expect, actual)           \
do{                                         \
    MyTestClass TEST;                       \
    if(!TEST.ExceptEqual(expect, actual)){  \
        ERROR_PRINT(expect,actual)          \
    }                                       \
}while(0)
 
#define PRINT_TEST_RESULT()                 \
do{                                         \
    MyTestClass TEST;                       \
    TEST.PrintResult();                     \
}while(0)

// MyJson.cpp : 定义控制台应用程序的入口点。
//
 
#include "stdafx.h"
#include "JsonParse.h"
#include <iostream>
#include "MyTestUnit.h"    
 
int main()
{
    MyJsonStruct js =InitJsonStruct("null");
    EXCEPT_EQ(DEF_PARSE_OK, DEFParse(js));
    EXCEPT_EQ(DEF_NULL, GetParseType(js));
 
    ResetJsonStruct("", js);
    EXCEPT_EQ(DEF_PARSE_EXPECT_VALUE, DEFParse(js));
    EXCEPT_EQ(DEF_NONE, GetParseType(js));
 
    ResetJsonStruct(" ", js);
    EXCEPT_EQ(DEF_PARSE_EXPECT_VALUE, DEFParse(js));
    EXCEPT_EQ(DEF_NONE, GetParseType(js));
 
 
    ResetJsonStruct("nul", js);
    EXCEPT_EQ(DEF_PARSE_INVALID_VALUE, DEFParse(js));
    EXCEPT_EQ(DEF_NONE, GetParseType(js));
 
    ResetJsonStruct("?", js);
    EXCEPT_EQ(DEF_PARSE_INVALID_VALUE, DEFParse(js));
    EXCEPT_EQ(DEF_NONE, GetParseType(js));
 
    ResetJsonStruct("null x", js);
    EXCEPT_EQ(DEF_PARSE_ROOT_NOT_SINGULAR, DEFParse(js));
    EXCEPT_EQ(DEF_NONE, GetParseType(js));
 
    PRINT_TEST_RESULT();
    return 0;
}