JsonParser.java

package z.net.json;

import z.net.json.core.DataCharBuffer;
import z.net.json.core.IndexBuffer;
import z.net.json.core.ParserException;

/**
 *
 */
public class JsonParser {

    private IndexBuffer   tokenBuffer   = null;
    private IndexBuffer   elementBuffer = null;
    private int           elementIndex  = 0;
    private JsonTokenizer jsonTokenizer = null;

    public JsonParser(IndexBuffer tokenBuffer, IndexBuffer elementBuffer) {
        this.tokenBuffer   = tokenBuffer;
        this.jsonTokenizer = new JsonTokenizer(this.tokenBuffer);
        this.elementBuffer = elementBuffer;
    }


    public void parse(DataCharBuffer dataBuffer) {
        this.elementIndex  = 0;

        this.jsonTokenizer.reinit(dataBuffer, this.tokenBuffer);

        parseObject(this.jsonTokenizer);

        this.elementBuffer.count = this.elementIndex;
    }

    private void parseObject(JsonTokenizer tokenizer) {
        assertHasMoreTokens(tokenizer);
        tokenizer.parseToken();
        assertThisTokenType(tokenizer.tokenType(), TokenTypes.JSON_CURLY_BRACKET_LEFT);
        setElementData     (tokenizer, ElementTypes.JSON_OBJECT_START);

        tokenizer.nextToken();
        tokenizer.parseToken();
        byte tokenType = tokenizer.tokenType();

        while( tokenType != TokenTypes.JSON_CURLY_BRACKET_RIGHT) {
            assertThisTokenType(tokenType, TokenTypes.JSON_STRING_TOKEN);
            setElementData(tokenizer, ElementTypes.JSON_PROPERTY_NAME);

            tokenizer.nextToken();
            tokenizer.parseToken();
            tokenType = tokenizer.tokenType();
            assertThisTokenType(tokenType, TokenTypes.JSON_COLON);

            tokenizer.nextToken();
            tokenizer.parseToken();
            tokenType = tokenizer.tokenType();


            switch(tokenType) {
                case TokenTypes.JSON_STRING_TOKEN        : { setElementData(tokenizer, ElementTypes.JSON_PROPERTY_VALUE_STRING);    } break;
                case TokenTypes.JSON_STRING_ENC_TOKEN    : { setElementData(tokenizer, ElementTypes.JSON_PROPERTY_VALUE_STRING_ENC);} break;
                case TokenTypes.JSON_NUMBER_TOKEN        : { setElementData(tokenizer, ElementTypes.JSON_PROPERTY_VALUE_NUMBER);    } break;
                case TokenTypes.JSON_BOOLEAN_TOKEN       : { setElementData(tokenizer, ElementTypes.JSON_PROPERTY_VALUE_BOOLEAN);   } break;
                case TokenTypes.JSON_NULL_TOKEN          : { setElementData(tokenizer, ElementTypes.JSON_PROPERTY_VALUE_NULL);      } break;
                case TokenTypes.JSON_CURLY_BRACKET_LEFT  : { parseObject(tokenizer); } break;
                case TokenTypes.JSON_SQUARE_BRACKET_LEFT : { parseArray(tokenizer); } break;
            }

            tokenizer.nextToken();
            tokenizer.parseToken();
            tokenType = tokenizer.tokenType();
            if(tokenType == TokenTypes.JSON_COMMA) {
                tokenizer.nextToken();  //skip , tokens if found here.
                tokenizer.parseToken();
                tokenType = tokenizer.tokenType();
            }

        }
        setElementData(tokenizer, ElementTypes.JSON_OBJECT_END);
    }

    private void parseArray(JsonTokenizer tokenizer) {
        setElementData(tokenizer, ElementTypes.JSON_ARRAY_START);

        tokenizer.nextToken();
        tokenizer.parseToken();

        while(tokenizer.tokenType() != TokenTypes.JSON_SQUARE_BRACKET_RIGHT) {

            byte tokenType = tokenizer.tokenType(); // extracted only for debug purposes.


            switch(tokenType) {
                case TokenTypes.JSON_STRING_TOKEN       : { setElementData(tokenizer, ElementTypes.JSON_ARRAY_VALUE_STRING);    } break;
                case TokenTypes.JSON_STRING_ENC_TOKEN   : { setElementData(tokenizer, ElementTypes.JSON_ARRAY_VALUE_STRING_ENC);} break;
                case TokenTypes.JSON_NUMBER_TOKEN       : { setElementData(tokenizer, ElementTypes.JSON_ARRAY_VALUE_NUMBER);    } break;
                case TokenTypes.JSON_BOOLEAN_TOKEN      : { setElementData(tokenizer, ElementTypes.JSON_ARRAY_VALUE_BOOLEAN);   } break;
                case TokenTypes.JSON_NULL_TOKEN         : { setElementData(tokenizer, ElementTypes.JSON_ARRAY_VALUE_NULL);      } break;
                case TokenTypes.JSON_CURLY_BRACKET_LEFT : { parseObject(tokenizer); } break;
                // todo add arrays in arrays support
            }


            tokenizer.nextToken();
            tokenizer.parseToken();
            tokenType = tokenizer.tokenType();
            if(tokenType == TokenTypes.JSON_COMMA) {
                tokenizer.nextToken();
                tokenizer.parseToken();
                tokenType = tokenizer.tokenType();
            }
        }

        setElementData(tokenizer, ElementTypes.JSON_ARRAY_END);
    }

    private void setElementData(JsonTokenizer tokenizer, byte elementType) {
        this.elementBuffer.position[this.elementIndex] = tokenizer.tokenPosition();
        this.elementBuffer.length  [this.elementIndex] = tokenizer.tokenLength();
        this.elementBuffer.type    [this.elementIndex] = elementType;
        this.elementIndex++;
    }

    private final void assertThisTokenType(byte tokenType, byte expectedTokenType) {
        if(tokenType != expectedTokenType) {
            throw new ParserException("Token type mismatch: Expected " + expectedTokenType + " but found " + tokenType);
        }
    }


    private void assertHasMoreTokens(JsonTokenizer tokenizer) {
        if(! tokenizer.hasMoreTokens()) {
            throw new ParserException("Expected more tokens available in the tokenizer");
        }
    }
}