godot/core/io/json.cpp

/*************************************************************************/
/*  json.cpp                                                             */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                    http://www.godotengine.org                         */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
/*                                                                       */
/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
/*************************************************************************/
#include "json.h"
#include "print_string.h"

const char * JSON::tk_name[TK_MAX] = {
	"'{'",
	"'}'",
	"'['",
	"']'",
	"identifier",
	"string",
	"number",
	"':'",
	"','",
	"EOF",
};



String JSON::_print_var(const Variant& p_var) {

	switch(p_var.get_type()) {

		case Variant::NIL: return "null";
		case Variant::BOOL: return p_var.operator bool() ? "true": "false";
		case Variant::INT: return itos(p_var);
		case Variant::REAL: return rtos(p_var);
		case Variant::INT_ARRAY:
		case Variant::REAL_ARRAY:
		case Variant::STRING_ARRAY:
		case Variant::ARRAY: {

			String s = "[";
			Array a = p_var;
			for(int i=0;i<a.size();i++) {
				if (i>0)
					s+=", ";
				s+=_print_var(a[i]);
			}
			s+="]";
			return s;
		};
		case Variant::DICTIONARY: {

			String s = "{";
			Dictionary d = p_var;
			List<Variant> keys;
			d.get_key_list(&keys);

			for (List<Variant>::Element *E=keys.front();E;E=E->next()) {

				if (E!=keys.front())
					s+=", ";
				s+=_print_var(String(E->get()));
				s+=":";
				s+=_print_var(d[E->get()]);
			}

			s+="}";
			return s;
		};
		default: return "\""+String(p_var).json_escape()+"\"";

	}

}

String JSON::print(const Variant& p_var) {

	return _print_var(p_var);
}


Error JSON::_get_token(const CharType *p_str, int &idx, int p_len, Token& r_token,int &line,String &r_err_str) {

	while (true) {
		switch(p_str[idx]) {

			case '\n': {

				line++;
				idx++;
				break;
			};
			case 0: {
				r_token.type=TK_EOF;
				return OK;
			} break;
			case '{': {

				r_token.type=TK_CURLY_BRACKET_OPEN;
				idx++;
				return OK;
			};
			case '}': {

				r_token.type=TK_CURLY_BRACKET_CLOSE;
				idx++;
				return OK;
			};
			case '[': {

				r_token.type=TK_BRACKET_OPEN;
				idx++;
				return OK;
			};
			case ']': {

				r_token.type=TK_BRACKET_CLOSE;
				idx++;
				return OK;
			};
			case ':': {

				r_token.type=TK_COLON;
				idx++;
				return OK;
			};
			case ',': {

				r_token.type=TK_COMMA;
				idx++;
				return OK;
			};
			case '"': {

				idx++;
				String str;
				while(true) {
					if (p_str[idx]==0) {
						r_err_str="Unterminated String";
						return ERR_PARSE_ERROR;
					} else if (p_str[idx]=='"') {
						idx++;
						break;
					} else if (p_str[idx]=='\\') {
						//escaped characters...
						idx++;
						CharType next = p_str[idx];
						if (next==0) {
							r_err_str="Unterminated String";
							return  ERR_PARSE_ERROR;
						}
						CharType res=0;

						switch(next) {

							case 'b': res=8; break;
							case 't': res=9; break;
							case 'n': res=10; break;
							case 'f': res=12; break;
							case 'r': res=13; break;
							case 'u': {
								//hexnumbarh - oct is deprecated


								for(int j=0;j<4;j++) {
									CharType c = p_str[idx+j+1];
									if (c==0) {
										r_err_str="Unterminated String";
										return ERR_PARSE_ERROR;
									}
									if (!((c>='0' && c<='9') || (c>='a' && c<='f') || (c>='A' && c<='F'))) {

										r_err_str="Malformed hex constant in string";
										return ERR_PARSE_ERROR;
									}
									CharType v;
									if (c>='0' && c<='9') {
										v=c-'0';
									} else if (c>='a' && c<='f') {
										v=c-'a';
										v+=10;
									} else if (c>='A' && c<='F') {
										v=c-'A';
										v+=10;
									} else {
										ERR_PRINT("BUG");
										v=0;
									}

									res<<=4;
									res|=v;


								}
								idx+=4; //will add at the end anyway


							} break;
							//case '\"': res='\"'; break;
							//case '\\': res='\\'; break;
							//case '/': res='/'; break;
							default: {
								res = next;
								//r_err_str="Invalid escape sequence";
								//return ERR_PARSE_ERROR;
							} break;
						}

						str+=res;

					} else {
						if (p_str[idx]=='\n')
							line++;
						str+=p_str[idx];
					}
					idx++;
				}

				r_token.type=TK_STRING;
				r_token.value=str;
				return OK;

			} break;
			default: {

				if (p_str[idx]<=32) {
					idx++;
					break;
				}

				if (p_str[idx]=='-' || (p_str[idx]>='0' && p_str[idx]<='9')) {
					//a number
					const CharType *rptr;
					double number = String::to_double(&p_str[idx],&rptr);
					idx+=(rptr - &p_str[idx]);
					r_token.type=TK_NUMBER;
					r_token.value=number;
					return OK;

				} else if ((p_str[idx]>='A' && p_str[idx]<='Z') || (p_str[idx]>='a' && p_str[idx]<='z')) {

					String id;

					while((p_str[idx]>='A' && p_str[idx]<='Z') || (p_str[idx]>='a' && p_str[idx]<='z')) {

						id+=p_str[idx];
						idx++;
					}

					r_token.type=TK_IDENTIFIER;
					r_token.value=id;
					return OK;
				} else {
					r_err_str="Unexpected character.";
					return ERR_PARSE_ERROR;
				}
			}

		}
	}

	return ERR_PARSE_ERROR;
}



Error JSON::_parse_value(Variant &value,Token& token,const CharType *p_str,int &index, int p_len,int &line,String &r_err_str) {


	if (token.type==TK_CURLY_BRACKET_OPEN) {

		Dictionary d(true);
		Error err = _parse_object(d,p_str,index,p_len,line,r_err_str);
		if (err)
			return err;
		value=d;
		return OK;
	} else if (token.type==TK_BRACKET_OPEN) {

		Array a(true);
		Error err = _parse_array(a,p_str,index,p_len,line,r_err_str);
		if (err)
			return err;
		value=a;
		return OK;

	} else if (token.type==TK_IDENTIFIER) {

		String id = token.value;
		if (id=="true")
			value=true;
		else if (id=="false")
			value=false;
		else if (id=="null")
			value=Variant();
		else {
			r_err_str="Expected 'true','false' or 'null', got '"+id+"'.";
			return ERR_PARSE_ERROR;
		}
		return OK;

	} else if (token.type==TK_NUMBER) {

		value=token.value;
		return OK;
	} else if (token.type==TK_STRING) {

		value=token.value;
		return OK;
	} else {
		r_err_str="Expected value, got "+String(tk_name[token.type])+".";
		return ERR_PARSE_ERROR;
	}

	return ERR_PARSE_ERROR;
}


Error JSON::_parse_array(Array &array,const CharType *p_str,int &index, int p_len,int &line,String &r_err_str) {

	Token token;
	bool need_comma=false;


	while(index<p_len) {

		Error err = _get_token(p_str,index,p_len,token,line,r_err_str);
		if (err!=OK)
			return err;

		if (token.type==TK_BRACKET_CLOSE) {

			return OK;
		}

		if (need_comma) {

			if (token.type!=TK_COMMA) {

				r_err_str="Expected ','";
				return ERR_PARSE_ERROR;
			} else {
				need_comma=false;
				continue;
			}
		}

		Variant v;
		err = _parse_value(v,token,p_str,index,p_len,line,r_err_str);
		if (err)
			return err;

		array.push_back(v);
		need_comma=true;

	}

	return OK;

}

Error JSON::_parse_object(Dictionary &object,const CharType *p_str,int &index, int p_len,int &line,String &r_err_str) {

	bool at_key=true;
	String key;
	Token token;
	bool need_comma=false;


	while(index<p_len) {


		if (at_key) {

			Error err = _get_token(p_str,index,p_len,token,line,r_err_str);
			if (err!=OK)
				return err;

			if (token.type==TK_CURLY_BRACKET_CLOSE) {

				return OK;
			}

			if (need_comma) {

				if (token.type!=TK_COMMA) {

					r_err_str="Expected '}' or ','";
					return ERR_PARSE_ERROR;
				} else {
					need_comma=false;
					continue;
				}
			}

			if (token.type!=TK_STRING) {


				r_err_str="Expected key";
				return ERR_PARSE_ERROR;
			}

			key=token.value;
			err = _get_token(p_str,index,p_len,token,line,r_err_str);
			if (err!=OK)
				return err;
			if (token.type!=TK_COLON) {

				r_err_str="Expected ':'";
				return ERR_PARSE_ERROR;
			}
			at_key=false;
		} else {


			Error err = _get_token(p_str,index,p_len,token,line,r_err_str);
			if (err!=OK)
				return err;

			Variant v;
			err = _parse_value(v,token,p_str,index,p_len,line,r_err_str);
			if (err)
				return err;
			object[key]=v;
			need_comma=true;
			at_key=true;
		}
	}

	return OK;
}


Error JSON::parse(const String& p_json, Variant &r_ret, String &r_err_str, int &r_err_line) {


	const CharType *str = p_json.ptr();
	int idx = 0;
	int len = p_json.length();
	Token token;
	r_err_line=0;
	String aux_key;

	Error err = _get_token(str,idx,len,token,r_err_line,r_err_str);
	if (err)
		return err;

	err = _parse_value(r_ret,token,str,idx,len,r_err_line,r_err_str);

	return err;
	

}