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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2015 Olaf Wintermann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef DAVQLPARSER_H
#define	DAVQLPARSER_H

#ifdef	__cplusplus
extern "C" {
#endif

#include <stdint.h>
#include "ucx/string.h"
#include "ucx/list.h"

/**
 * Enumeration of possible statement types.
 */
typedef enum {DAVQL_ERROR, DAVQL_GET, DAVQL_SET} davqltype_t;

/**
 * Enumeration of possible expression types.
 */
typedef enum {
    DAVQL_LITERAL, DAVQL_IDENTIFIER,
    DAVQL_UNARY, DAVQL_BINARY, DAVQL_LOGICAL, DAVQL_FUNCCALL
} davqlexprtype_t;

/**
 * Enumeration of possible expression operators.
 */
typedef enum {
    DAVQL_NOOP, DAVQL_CALL, DAVQL_ARGLIST, // internal representations
    DAVQL_ADD, DAVQL_SUB, DAVQL_MUL, DAVQL_DIV,
    DAVQL_AND, DAVQL_OR, DAVQL_XOR, DAVQL_NEG,  // airthmetic
    DAVQL_NOT, DAVQL_LAND, DAVQL_LOR, DAVQL_LXOR, // logical
    DAVQL_EQ, DAVQL_NEQ, DAVQL_LT, DAVQL_GT, DAVQL_LE, DAVQL_GE,
    DAVQL_LIKE, DAVQL_UNLIKE // comparisons
} davqloperator_t;

/**
 * An expression within a DAVQL query.
 */
typedef struct _davqlexpr DavQLExpression;

/**
 * The structure for type DavQLExpression.
 */
struct _davqlexpr {
    /**
     * The original expression text.
     * Contains the literal value, if type is LITERAL.
     */
    sstr_t srctext;
    /**
     * The expression type.
     */
    davqlexprtype_t type;
    /**
     * Operator.
     * 
     */
    davqloperator_t op;
    /**
     * Left or single operand.
     * <code>NULL</code> for literals or identifiers.
     */
    DavQLExpression *left;
    /**
     * Right operand.
     * <code>NULL</code> for literals, identifiers or unary expressions.
     */
    DavQLExpression *right;
};


/**
 * Query statement object.
 * Contains the binary information about the parsed query.
 * 
 * The grammar for a DavQLStatement is:
 * 
 * <pre>
 * Expression = Expression, BinaryOperator, Expression
 *            | UnaryOperator, Expression
 *            | FunctionCall | Identifier | Literal
 *            | "(", Expression, ")";
 * 
 * FunctionCall    = Identifier, "(", ArgumentList, ")";
 * ArgumentList    = Expression, {",", Expression};
 * Identifier      = IdentifierChar - ?Digit?, {IdentifierChar}
 *                 | "`", ?Character?, {?Character?}, "`";
 * IdentifierChar  = ?Character - (" "|",")?;
 * Literal         = Number | String;
 * Number          = ?Digit?, {?Digit?} | "%d";
 * String          = "'", {?Character - "'"? | "'''"} , "'";
 * 
 * LogicalExpression = LogicalExpression, LogicalOperator, LogicalExpression
 *                   | "not ", LogicalExpression
 *                   | Expression, Comparison, Expression
 *                   | Expression, (" like " | " unlike "), String
 *                   | "(", LogicalExpression, ")";
 * 
 * UnaryOperator   = "-" | "~";
 * BinaryOperator  = "+" | "-" | "*" | "/" | "&" | "|" | "^";
 * LogicalOperator = " and " | " or " | " xor ";
 * Comparison      = | "=" | "<" | ">" | "<=" | ">=" | "!=";
 * 
 * FieldExpressions = "*", {",", Expression, " as ", String}
 *                  | FieldExpression, {",", FieldExpression}
 *                  | "-";
 * FieldExpression  = Identifier
 *                  | Expression, " as ", String;
 * SetExpressions   = SetExpression, {",", SetExpressions};
 * SetExpression    = Identifier, "=", Expression;
 * 
 * WithClause = "depth", "=", (Number | "infinity");
 * 
 * OrderByClause    = OrderByCriterion, {",", OrderByCriterion};
 * OrderByCriterion = (Identifier | Number), [" asc"|" desc"];
 * 
 * </pre>
 * 
 * Note: mandatory spaces are part of the grammar. But you may also insert an
 * arbitrary amount of optional spaces between two symbols if they are not part
 * of an literal or identifier.
 * 
 * <b>GET:</b>
 * <pre>
 * GetStatement = "get ", FieldExpressions,
 * " from ", Identifier,
 * [" with ", WithClause],
 * [" where ", LogicalExpression],
 * [" order by ", OrderByClause];
  * </pre>
 * 
 * <b>SET:</b>
 * <pre>
 * "set ",SetExpressions,
 * " at ", Identifier,
 * [" with ", WithClause],
 * (" where ", LogicalExpression) | " anywhere";
 * </pre>
 * 
 */
typedef struct {
    /**
     * The original query text.
     */
    sstr_t srctext;
    /**
     * The statement type.
     */
    davqltype_t type;
    /**
     * Error code, if any error occurred. Zero otherwise.
     */
    int errorcode;
    /**
     * Error message, if any error occurred.
     */
    char* errormessage;
    /**
     * The list of field expressions.
     */
    UcxList* fields;
    /**
     * The list of DavQLExpressions for the new DAV property values.
     * This is <code>NULL</code> for GET queries.
     */
    UcxList* setvalues;
    /**
     * A string that denotes the queried path.
     */
    sstr_t path;
    /**
     * Logical expression for selection.
     * <code>NULL</code>, if there is no where clause.
     */
    DavQLExpression* where;
    /**
     * The recursion depth for the statement.
     * Defaults to 1.
     */
    int depth;
} DavQLStatement;

/** Infinity recursion depth for a DavQLStatement. */
#define DAV_DEPTH_INFINITY -1

/** Expected an identifier, but found something else. */
#define DAVQL_ERROR_IDENTIFIER_EXPECTED 10

/** The with-clause contains an unknown attribute. */
#define DAVQL_ERROR_UNKNOWN_ATTRIBUTE 20

/** Depth must be greater than zero or infinity. */
#define DAVQL_ERROR_INVALID_DEPTH 21

/** The with-clause contains an attribute more than once. */
#define DAVQL_ERROR_DUPLICATED_ATTRIBUTE 29

/** A quote symbol (' or `) is missing. */
#define DAVQL_ERROR_MISSING_QUOTE 50

/** No more tokens to parse, but the parser expected more. */
#define DAVQL_ERROR_UNEXPECTED_END 100

/** A token was found, which has not been expected. */
#define DAVQL_ERROR_UNEXPECTED_TOKEN 101

/** Nothing about the statement seems legit. */
#define DAVQL_ERROR_INVALID -1

/**
 * Starts an interactive debugger for a DavQLStatement.
 * 
 * @param stmt the statement to debug
 */
void dav_debug_statement(DavQLStatement *stmt);

/**
 * Parses a statement.
 * @param stmt the sstr_t containing the statement
 * @return a DavQLStatement object
 */
DavQLStatement* dav_parse_statement(sstr_t stmt);

/**
 * Implicitly converts a cstr to a sstr_t and calls dav_parse_statement.
 */
#define dav_parse_cstr_statement(stmt) dav_parse_statement(S(stmt))

/**
 * Frees a DavQLStatement.
 * @param stmt the statement object to free
 */
void dav_free_statement(DavQLStatement *stmt);

#ifdef	__cplusplus
}
#endif

#endif	/* DAVQLPARSER_H */