sems/apps/jsonrpc/jsonxx.cpp

// Author: Hong Jiang <hong@hjiang.net>

#include "jsonxx.h"

#include <cctype>
#include <iostream>
#include <sstream>

namespace jsonxx {

void eat_whitespaces(std::istream& input) {
    char ch;
    do {
        input.get(ch);
    } while(isspace(ch));
    input.putback(ch);
}

// Try to consume characters from the input stream and match the
// pattern string. Leading whitespaces from the input are ignored if
// ignore_ws is true.
bool match(const std::string& pattern, std::istream& input,
           bool ignore_ws) {
    if (ignore_ws) {
        eat_whitespaces(input);
    }
    std::string::const_iterator cur(pattern.begin());
    char ch(0);
    while(input && !input.eof() && cur != pattern.end()) {
        input.get(ch);
        if (ch != *cur) {
            input.putback(ch);
            return false;
        } else {
            cur++;
        }
    }
    return cur == pattern.end();
}

bool parse_string(std::istream& input, std::string* value) {
    if (!match("\"", input))  {
        return false;
    }
    char ch;
    while(!input.eof() && input.good()) {
        input.get(ch);
        if (ch == '"') {
            break;
        }
        value->push_back(ch);
    }
    if (input && ch == '"') {
        return true;
    } else {
        return false;
    }
}

bool parse_bool(std::istream& input, bool* value) {
    if (match("true", input))  {
        *value = true;
        return true;
    }
    if (match("false", input)) {
        *value = false;
        return true;
    }
    return false;
}

bool parse_null(std::istream& input) {
    if (match("null", input))  {
        return true;
    }
    return false;
}

bool parse_float(std::istream& input, double* value) {
    eat_whitespaces(input);
    char ch;
    bool has_dot = false;
    std::string value_str;
    int sign = 1;
    if (match("-", input)) {
        sign = -1;
    } else {
        match("+", input);
    }
    while(input && !input.eof()) {
        input.get(ch);
	if (ch=='.')
	  has_dot = true;
        if (!isdigit(ch) && (!(ch == '.'))) {
            input.putback(ch);
            break;
        }
        value_str.push_back(ch);
    }
    if (!has_dot) {
      for (std::string::reverse_iterator r_it=
	     value_str.rbegin(); r_it != value_str.rend(); r_it++)
	input.putback(*r_it);
      return false;
    }
    if (value_str.size() > 0) {
        std::istringstream(value_str) >> *value;
	*value*=sign;
        return true;
    } else {
        return false;
    }
}

bool parse_number(std::istream& input, long* value) {
    eat_whitespaces(input);
    char ch;
    std::string value_str;
    int sign = 1;
    if (match("-", input)) {
        sign = -1;
    } else {
        match("+", input);
    }
    while(input && !input.eof()) {
        input.get(ch);
        if (!isdigit(ch)) {
            input.putback(ch);
            break;
        }
        value_str.push_back(ch);
    }
    if (value_str.size() > 0) {
        std::istringstream(value_str) >> *value;
	*value*=sign;
        return true;
    } else {
        return false;
    }
}

bool parse_number(std::istream& input, int* value) {
    eat_whitespaces(input);
    char ch;
    std::string value_str;
    int sign = 1;
    if (match("-", input)) {
        sign = -1;
    } else {
        match("+", input);
    }
    while(input && !input.eof()) {
        input.get(ch);
        if (!isdigit(ch)) {
            input.putback(ch);
            break;
        }
        value_str.push_back(ch);
    }
    if (value_str.size() > 0) {
        std::istringstream(value_str) >> *value;
	*value*=sign;
        return true;
    } else {
        return false;
    }
}

Object::Object() : value_map_() {}

Object::~Object() {
    std::map<std::string, Value*>::iterator i;
    for (i = value_map_.begin(); i != value_map_.end(); ++i) {
        delete i->second;
    }
}

bool Object::parse(std::istream& input) {
    if (!match("{", input)) {
        return false;
    }

    do {
        std::string key;
        if (!parse_string(input, &key)) {
            return false;
        }
        if (!match(":", input)) {
            return false;
        }
        Value* v = new Value();
        if (!v->parse(input)) {
            delete v;
            break;
        }
        value_map_[key] = v;
    } while (match(",", input));

    if (!match("}", input)) {
        return false;
    }
    return true;
}

Value::Value() : type_(INVALID_) {}

Value::~Value() {
    if (type_ == STRING_) {
        delete string_value_;
    }
    if (type_ == OBJECT_) {
        delete object_value_;
    }
    if (type_ == ARRAY_) {
        delete array_value_;
    }
}

bool Value::parse(std::istream& input) {
    std::string string_value;
    if (parse_string(input, &string_value)) {
        string_value_ = new std::string();
        string_value_->swap(string_value);
        type_ = STRING_;
        return true;
    }
    if (parse_number(input, &integer_value_)) {
        type_ = INTEGER_;
        return true;
    }

    if (parse_bool(input, &bool_value_)) {
        type_ = BOOL_;
        return true;
    }
    if (parse_null(input)) {
        type_ = NULL_;
        return true;
    }
    array_value_ = new Array();
    if (array_value_->parse(input)) {
        type_ = ARRAY_;
        return true;
    }
    delete array_value_;
    object_value_ = new Object();
    if (object_value_->parse(input)) {
        type_ = OBJECT_;
        return true;
    }
    delete object_value_;
    return false;
}

Array::Array() : values_() {}

Array::~Array() {
    for (unsigned int i = 0; i < values_.size(); ++i) {
        delete values_[i];
    }
}

bool Array::parse(std::istream& input) {
    if (!match("[", input)) {
        return false;
    }

    do {
        Value* v = new Value();
        if (!v->parse(input)) {
            delete v;
            break;
        }
        values_.push_back(v);
    } while (match(",", input));

    if (!match("]", input)) {
        return false;
    }
    return true;
}

}  // namespace jsonxx