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454 lines
16 KiB
454 lines
16 KiB
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/*
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* Developed by Rafa Garcia <rafagarcia77@gmail.com>
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*
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* tiny-json.c is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* tiny-json.c is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with tiny-json.c. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include <string.h>
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#include "tiny-json.h"
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/** Structure to handle a heap of JSON properties. */
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typedef struct jsonPool_s {
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json_t* const mem; /**< Pointer to array of json properties. */
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unsigned int const qty; /**< Length of the array of json properties. */
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unsigned int nextFree; /**< The index of the next free json property. */
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} jsonPool_t;
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/* Search a property by its name in a JSON object. */
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json_t const* json_getProperty( json_t const* obj, char const* property ) {
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json_t const* sibling;
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for( sibling = obj->u.child; sibling; sibling = sibling->sibling )
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if ( sibling->name && !strcmp( sibling->name, property ) )
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return sibling;
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return 0;
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}
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/* Search a property by its name in a JSON object and return its value. */
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char const* json_getPropertyValue( json_t const* obj, char const* property ) {
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json_t const* field = json_getProperty( obj, property );
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if ( !field ) return 0;
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return json_getValue( field );
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}
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/* Internal prototypes: */
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static char* goBlank( char* str );
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static bool isNum( unsigned char ch );
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static char* goNum( char* str );
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static json_t* poolInit( jsonPool_t* pool );
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static json_t* poolNew( jsonPool_t* pool );
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static char* objValue( char* ptr, json_t* obj, jsonPool_t* pool );
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static char* setToNull( char* ch );
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static bool isEndOfPrimitive( char ch );
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/* Parse a string to get a json. */
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json_t const* json_create( char* str, json_t mem[], unsigned int qty ) {
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char* ptr = goBlank( str );
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if ( !ptr || *ptr != '{' ) return 0;
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jsonPool_t pool = { .mem = mem, .qty = qty };
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json_t* obj = poolInit( &pool );
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obj->name = 0;
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obj->sibling = 0;
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obj->u.child = 0;
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ptr = objValue( ptr, obj, &pool );
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if ( !ptr ) return 0;
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return obj;
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}
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/** Get a special character with its escape character. Examples:
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* 'b' -> '\b', 'n' -> '\n', 't' -> '\t'
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* @param ch The escape character.
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* @return The character code. */
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static char getEscape( char ch ) {
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static struct { char ch; char code; } const pair[] = {
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{ '\"', '\"' },
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{ '\\', '\\' },
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{ '/', '/' },
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{ 'b', '\b' },
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{ 'f', '\f' },
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{ 'n', '\n' },
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{ 'r', '\r' },
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{ 't', '\t' },
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};
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unsigned int i;
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for( i = 0; i < sizeof pair / sizeof *pair; ++i )
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if ( pair[i].ch == ch )
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return pair[i].code;
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return '\0';
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}
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/** Check if a character is a hexadecimal digit. */
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static bool isHexaDigit( unsigned char nibble ) {
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if ( nibble < '0' ) return false;
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if ( nibble <= '9' ) return true;
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if ( nibble < 'A' ) return false;
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if ( nibble <= 'F' ) return true;
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if ( nibble < 'a' ) return false;
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if ( nibble <= 'f' ) return true;
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return false;
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}
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/** Parse 4 charcters.
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* @Param str Pointer to first digit.
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* @retval '?' If the four characters are hexadecimal digits.
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* @retcal '\0' In other cases. */
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static char getCharFromUnicode( char const* str ) {
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unsigned int i;
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for( i = 0; i < 4; ++i )
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if ( !isHexaDigit( str[i] ) )
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return '\0';
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return '?';
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}
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/** Parse a string and replace the scape characters by their meaning characters.
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* This parser stops when finds the character '\"'. Then replaces '\"' by '\0'.
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* @param str Pointer to first character.
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* @retval Pointer to first non white space after the string. If success.
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* @retval Null pointer if any error occur. */
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static char* parseString( char* str ) {
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char* head = str;
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char* tail = str;
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for( ; *head >= ' '; ++head, ++tail ) {
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if ( *head == '\"' ) {
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*tail = '\0';
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return ++head;
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}
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if ( *head == '\\' ) {
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if ( *++head == 'u' ) {
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char const ch = getCharFromUnicode( ++head );
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if ( ch == '\0' ) return 0;
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*tail = ch;
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head += 3;
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}
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else {
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char const esc = getEscape( *head );
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if ( esc == '\0' ) return 0;
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*tail = esc;
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}
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}
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else *tail = *head;
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}
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return 0;
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}
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/** Parse a string to get the name of a property.
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* @param str Pointer to first character.
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* @param property The property to assign the name.
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* @retval Pointer to first of property value. If success.
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* @retval Null pointer if any error occur. */
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static char* propertyName( char* ptr, json_t* property ) {
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property->name = ++ptr;
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ptr = parseString( ptr );
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if ( !ptr ) return 0;
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ptr = goBlank( ptr );
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if ( !ptr ) return 0;
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if ( *ptr++ != ':' ) return 0;
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return goBlank( ptr );
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}
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/** Parse a string to get the value of a property when its type is JSON_TEXT.
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* @param str Pointer to first character ('\"').
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* @param property The property to assign the name.
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* @retval Pointer to first non white space after the string. If success.
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* @retval Null pointer if any error occur. */
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static char* textValue( char* ptr, json_t* property ) {
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++property->u.value;
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ptr = parseString( ++ptr );
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if ( !ptr ) return 0;
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property->type = JSON_TEXT;
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return ptr;
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}
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/** Compare two strings until get the null character in the second one.
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* @param ptr sub string
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* @param str main string
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* @retval Pointer to next chraracter.
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* @retval Null pointer if any error occur. */
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static char* checkStr( char* ptr, char const* str ) {
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while( *str )
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if ( *ptr++ != *str++ )
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return 0;
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return ptr;
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}
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/** Parser a string to get a primitive value.
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* If the first character after the value is diferent of '}' or ']' is set to '\0'.
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* @param str Pointer to first character.
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* @param property Property handler to set the value and the type, (true, false or null).
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* @param value String with the primitive literal.
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* @param type The code of the type. ( JSON_BOOLEAN or JSON_NULL )
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* @retval Pointer to first non white space after the string. If success.
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* @retval Null pointer if any error occur. */
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static char* primitiveValue( char* ptr, json_t* property, char const* value, jsonType_t type ) {
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ptr = checkStr( ptr, value );
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if ( !ptr || !isEndOfPrimitive( *ptr ) ) return 0;
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ptr = setToNull( ptr );
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property->type = type;
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return ptr;
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}
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/** Parser a string to get a true value.
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* If the first character after the value is diferent of '}' or ']' is set to '\0'.
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* @param str Pointer to first character.
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* @param property Property handler to set the value and the type, (true, false or null).
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* @retval Pointer to first non white space after the string. If success.
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* @retval Null pointer if any error occur. */
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static char* trueValue( char* ptr, json_t* property ) {
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return primitiveValue( ptr, property, "true", JSON_BOOLEAN );
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}
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/** Parser a string to get a false value.
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* If the first character after the value is diferent of '}' or ']' is set to '\0'.
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* @param str Pointer to first character.
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* @param property Property handler to set the value and the type, (true, false or null).
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* @retval Pointer to first non white space after the string. If success.
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* @retval Null pointer if any error occur. */
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static char* falseValue( char* ptr, json_t* property ) {
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return primitiveValue( ptr, property, "false", JSON_BOOLEAN );
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}
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/** Parser a string to get a null value.
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* If the first character after the value is diferent of '}' or ']' is set to '\0'.
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* @param str Pointer to first character.
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* @param property Property handler to set the value and the type, (true, false or null).
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* @retval Pointer to first non white space after the string. If success.
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* @retval Null pointer if any error occur. */
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static char* nullValue( char* ptr, json_t* property ) {
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return primitiveValue( ptr, property, "null", JSON_NULL );
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}
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/** Analyze the exponential part of a real number.
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* @param str Pointer to first character.
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* @retval Pointer to first non numerical after the string. If success.
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* @retval Null pointer if any error occur. */
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static char* expValue( char* ptr ) {
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if ( *ptr == '-' || *ptr == '+' ) ++ptr;
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if ( !isNum( *ptr ) ) return 0;
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ptr = goNum( ++ptr );
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return ptr;
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}
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/** Analyze the decimal part of a real number.
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* @param str Pointer to first character.
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* @retval Pointer to first non numerical after the string. If success.
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* @retval Null pointer if any error occur. */
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static char* fraqValue( char* ptr ) {
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if ( !isNum( *ptr ) ) return 0;
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ptr = goNum( ++ptr );
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if ( !ptr ) return 0;
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return ptr;
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}
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/** Parser a string to get a numerical value.
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* If the first character after the value is diferent of '}' or ']' is set to '\0'.
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* @param str Pointer to first character.
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* @param property Property handler to set the value and the type: JSON_REAL or JSON_INTEGER.
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* @retval Pointer to first non white space after the string. If success.
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* @retval Null pointer if any error occur. */
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static char* numValue( char* ptr, json_t* property ) {
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if ( *ptr == '-' ) ++ptr;
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if ( *ptr != '0' ) {
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ptr = goNum( ptr );
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if ( !ptr ) return 0;
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}
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else if ( isNum( *++ptr ) ) return 0;
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property->type = JSON_INTEGER;
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if ( *ptr == '.' ) {
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ptr = fraqValue( ++ptr );
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if ( !ptr ) return 0;
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property->type = JSON_REAL;
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}
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if ( *ptr == 'e' || *ptr == 'E' ) {
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ptr = expValue( ++ptr );
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if ( !ptr ) return 0;
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property->type = JSON_REAL;
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}
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if ( !isEndOfPrimitive( *ptr ) ) return 0;
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if ( JSON_INTEGER == property->type ) {
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char const* value = property->u.value;
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bool const negative = *value == '-';
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unsigned int const maxdigits = negative ? 20: 19;
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unsigned int const len = ptr - value;
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if ( len > maxdigits ) return 0;
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if ( len == maxdigits ) {
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char const tmp = *ptr;
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*ptr = '\0';
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char const* const min = "-9223372036854775808";
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char const* const max = "9223372036854775807";
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char const* const threshold = negative ? min: max;
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if ( 0 > strcmp( threshold, value ) ) return 0;
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*ptr = tmp;
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}
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}
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ptr = setToNull( ptr );
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return ptr;
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}
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/** Add a property to a JSON object or array.
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* @param obj The handler of the JSON object or array.
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* @param property The handler of the property to be added. */
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static void add( json_t* obj, json_t* property ) {
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property->sibling = 0;
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if ( !obj->u.child ) obj->u.child = property;
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else {
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json_t* iter;
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for( iter = obj->u.child; iter->sibling; iter = iter->sibling );
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iter->sibling = property;
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}
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}
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/** Parser a string to get a json object value.
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* @param str Pointer to first character.
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* @param pool The handler of a json pool for creating json instances.
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* @retval Pointer to first character after the value. If success.
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* @retval Null pointer if any error occur. */
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static char* objValue( char* ptr, json_t* obj, jsonPool_t* pool ) {
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obj->type = JSON_OBJ;
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obj->u.child = 0;
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obj->sibling = 0;
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ptr++;
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for(;;) {
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ptr = goBlank( ptr );
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if ( !ptr ) return 0;
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char const endchar = ( obj->type == JSON_OBJ )? '}': ']';
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if ( *ptr == endchar ) {
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*ptr = '\0';
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json_t* parentObj = obj->sibling;
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if ( !parentObj ) return ++ptr;
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obj->sibling = 0;
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obj = parentObj;
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++ptr;
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continue;
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}
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if ( *ptr == ',' ) {
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ptr = goBlank( ++ptr );
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if ( !ptr ) return 0;
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}
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json_t* property = poolNew( pool );
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if ( !property ) return 0;
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if( obj->type != JSON_ARRAY ) {
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if ( *ptr != '\"' ) return 0;
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ptr = propertyName( ptr, property );
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if ( !ptr ) return 0;
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}
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else property->name = 0;
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add( obj, property );
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property->u.value = ptr;
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switch( *ptr ) {
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case '{':
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property->type = JSON_OBJ;
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property->u.child = 0;
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property->sibling = obj;
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obj = property;
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++ptr;
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break;
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case '[':
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property->type = JSON_ARRAY;
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property->u.child = 0;
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property->sibling = obj;
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obj = property;
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++ptr;
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break;
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case '\"': ptr = textValue( ptr, property ); break;
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case 't': ptr = trueValue( ptr, property ); break;
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case 'f': ptr = falseValue( ptr, property ); break;
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case 'n': ptr = nullValue( ptr, property ); break;
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default: ptr = numValue( ptr, property ); break;
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}
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if ( !ptr ) return 0;
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}
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}
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/** Initialize a json pool.
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* @param pool The handler of the pool.
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* @return a instace of a json. */
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static json_t* poolInit( jsonPool_t* pool ) {
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pool->nextFree = 1;
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return &pool->mem[0];
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}
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/** Create an instance of a json from a pool.
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* @param pool The handler of the pool.
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* @retval The handler of the new instance if success.
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* @retval Null pointer if the pool was empty. */
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static json_t* poolNew( jsonPool_t* pool ) {
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if ( pool->nextFree >= pool->qty ) return 0;
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return &pool->mem[pool->nextFree++];
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}
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/** Checks whether an character belongs to set.
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* @param ch Character value to be checked.
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* @param set Set of characters. It is just a null-terminated string.
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* @return true or false there is membership or not. */
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static bool isOneOfThem( char ch, char const* set ) {
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while( *set != '\0' )
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if ( ch == *set++ )
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return true;
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return false;
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}
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/** Increases a pointer while it points to a character that belongs to a set.
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* @param str The initial pointer value.
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* @param set Set of characters. It is just a null-terminated string.
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* @return The final pointer value or null pointer if the null character was found. */
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static char* goWhile( char* str, char const* set ) {
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for(; *str != '\0'; ++str ) {
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if ( !isOneOfThem( *str, set ) )
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return str;
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}
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return 0;
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}
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/** Set of characters that defines a blank. */
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static char const* const blank = " \n\r\t\f";
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/** Increases a pointer while it points to a white space character.
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* @param str The initial pointer value.
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* @return The final pointer value or null pointer if the null character was found. */
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static char* goBlank( char* str ) {
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return goWhile( str, blank );
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}
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/** Checks if a character is a decimal digit. */
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static bool isNum( unsigned char ch ) {
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return ch >= '0' && ch <= '9';
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}
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/** Increases a pointer while it points to a decimal digit character.
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* @param str The initial pointer value.
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* @return The final pointer value or null pointer if the null character was found. */
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static char* goNum( char* str ) {
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for( ; *str != '\0'; ++str ) {
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if ( !isNum( *str ) )
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return str;
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}
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return 0;
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}
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/** Set of characters that defines the end of an array or a JSON object. */
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static char const* const endofblock = "}]";
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/** Set a char to '\0' and increase its pointer if the char is diferent to '}' or ']'.
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* @param ch Pointer to character.
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* @return Final value pointer. */
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static char* setToNull( char* ch ) {
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if ( !isOneOfThem( *ch, endofblock ) ) *ch++ = '\0';
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return ch;
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}
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/** Indicate if a character is the end of a primitive value. */
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static bool isEndOfPrimitive( char ch ) {
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return ch == ',' || isOneOfThem( ch, blank ) || isOneOfThem( ch, endofblock );
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} |