// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
/**
 * @author <a href="mailto:tonyv@yahoo-inc.com">tonyv</a>
 */
options {
    LOOKAHEAD = 1;
    STATIC = false;
    UNICODE_INPUT = true;
}

PARSER_BEGIN(Parser)
package com.yahoo.search.query.textserialize.parser;

import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.LinkedHashMap;

public class Parser {
    private DispatchFormHandler dispatchFormHandler;
    private Object dispatchContext;

    public Parser(java.io.Reader stream, DispatchFormHandler dispatchFormHandler, Object dispatchContext) {
        this(stream);
        this.dispatchFormHandler = dispatchFormHandler;
        this.dispatchContext = dispatchContext;
    }

    private static String parseString(String in) {
        return stripEnclosingQuotes(
            in.replace("\\\\", "\\").replace("\\\"", "\""));
    }

    private static String stripEnclosingQuotes(String in) {
        return in.substring(1, in.length() - 1);
    }
}

PARSER_END(Parser)

Object start():
{
    final Object result;
}
{
    result = form()
    <EOF>

    { return result; }
}

Object form():
{
    final Object result;
}
{
    (
    result = dispatchForm() |
    result = map() |
    result = array() |
    result = literal()
    )

    { return result; }
}

Object literal():
{
    final Object result;
}
{
    (
    result = string() |
    result = number() |
    result = bool() |
    result = null_()
    )

    { return result; }
}

String string():
{
    Token t;
}
{
    t = <STRING>
    { return parseString(t.image); }
}

Double number():
{
    Token t;
}
{
    t = <NUMBER>
    { return Double.valueOf(t.image); }
}

Boolean bool():
{
    Token t;
}
{
    t = <BOOLEAN>

    {
     if ("on".equals(t.image)) return true;
     return Boolean.valueOf(t.image);
    }
}

Object null_():
{}
{
    <NULL>
    { return null; }
}

Map<Object, Object> map():
{
    Object key, value;
    Map<Object, Object> result = new LinkedHashMap<Object, Object>();
}
{
    <OPEN_CURLY>
    (
       key = form()
       value = form()

       { result.put(key, value); }
    )*
    <CLOSE_CURLY>

    { return result; }
}

Object dispatchForm():
{
    Token symbol;
    List<Object> arguments;
}
{
    <OPEN_PAREN>
    symbol = <SYMBOL>
    arguments = forms()
    <CLOSE_PAREN>

    { return dispatchFormHandler.dispatch(symbol.image, arguments, dispatchContext); }
}

List<Object> forms():
{
    Object value;
    List<Object> results = new ArrayList<Object>();
}
{
    (
        value = form()
        { results.add(value); }
    )*

    { return results; }
}

List<Object> array():
{
    List<Object> result;
}
{
    <OPEN_SQUARE>
    result = forms()
    <CLOSE_SQUARE>

    { return result; }
}

SKIP : { " " | "\n" | "\r" | "\t" | "\f" | "," }

TOKEN : { < OPEN_PAREN: "(" > }
TOKEN : { < CLOSE_PAREN: ")" > }
TOKEN : { < OPEN_CURLY: "{" > }
TOKEN : { < CLOSE_CURLY: "}" > }
TOKEN : { < OPEN_SQUARE: "[" > }
TOKEN : { < CLOSE_SQUARE: "]" > }

TOKEN : { <BOOLEAN: "true" | "false" | "on" | "off" > }
TOKEN : { <NULL: "null" > }

TOKEN : { < STRING: <QUOTE> (<STRING_CHARACTER>)* <QUOTE> > }
TOKEN : { < #STRING_CHARACTER: "\\\\" | "\\\"" | ~["\"", "\\"] > }
TOKEN : { < #QUOTE: "\"" > }

TOKEN : { < NUMBER: (<SIGN>)? (<DIGIT>)+ ("." (<DIGIT>)*)? (<EXPONENT>)? > }
TOKEN : { < #EXPONENT: ["e", "E"] (<SIGN>)? (<DIGIT>)+ > }
TOKEN : { < #SIGN: ["+", "-"] >}
TOKEN : { < #DIGIT: ["0" - "9"] > }

TOKEN : { < SYMBOL: <SYMBOL_FIRST> (<SYMBOL_REST>)* > }
TOKEN : { < #SYMBOL_FIRST: ["a"-"z"] | ["A"-"Z"] |
        "+" | "-" | "*" | "/" |
        "!" | "?" |
        "-" | "_" |
        "=" | ">" | "<"  > }
TOKEN : { < #SYMBOL_REST: <SYMBOL_FIRST> | ["0" - "9"] | "." > }