diff -r 2483f517c562 -r b5bb7b3cd597 libidav/davqlparser.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libidav/davqlparser.h	Mon Jan 22 17:27:47 2024 +0100
@@ -0,0 +1,374 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2018 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 <cx/string.h>
+#include <cx/list.h>
+
+/**
+ * Enumeration of possible statement types.
+ */
+typedef enum {DAVQL_ERROR, DAVQL_SELECT, DAVQL_SET} davqltype_t;
+
+/**
+ * Enumeration of possible token classes.
+ */
+typedef enum {
+    DAVQL_TOKEN_INVALID, DAVQL_TOKEN_KEYWORD,
+    DAVQL_TOKEN_IDENTIFIER, DAVQL_TOKEN_FMTSPEC,
+    DAVQL_TOKEN_STRING, DAVQL_TOKEN_NUMBER, DAVQL_TOKEN_TIMESTAMP,
+    DAVQL_TOKEN_COMMA, DAVQL_TOKEN_OPENP, DAVQL_TOKEN_CLOSEP,
+    DAVQL_TOKEN_OPERATOR, DAVQL_TOKEN_END
+} davqltokenclass_t;
+
+/**
+ * Enumeration of possible expression types.
+ */
+typedef enum {
+    DAVQL_UNDEFINED_TYPE,
+    DAVQL_NUMBER, DAVQL_STRING, DAVQL_TIMESTAMP, 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;
+
+typedef struct DavQLToken DavQLToken;    
+struct DavQLToken {
+    davqltokenclass_t tokenclass;
+    cxstring value;
+    DavQLToken *prev;
+    DavQLToken *next;
+};
+
+/**
+ * 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.
+     */
+    cxstring 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;
+};
+
+/**
+ * A tuple representing an order criterion.
+ */
+typedef struct {
+    /**
+     * The column.
+     */
+    DavQLExpression *column;
+    /**
+     * True, if the result shall be sorted descending, false otherwise.
+     * Default is false (ascending).
+     */
+    _Bool descending;
+} DavQLOrderCriterion;
+
+/**
+ * A tuple representing a field.
+ */
+typedef struct {
+    /**
+     * The field name.
+     * <ul>
+     * <li>SELECT: the identifier or an alias name</li>
+     * <li>SET: the identifier</li>
+     * </ul>
+     */
+    cxstring name;
+    /**
+     * The field expression.
+     * <ul>
+     * <li>SELECT: the queried property (identifier) or an expression</li>
+     * <li>SET: the expression for the value to be set</li>
+     * </ul>
+     */
+    DavQLExpression *expr;
+} DavQLField;
+
+/**
+ * Query statement object.
+ * Contains the binary information about the parsed query.
+ * 
+ * The grammar for a DavQLStatement is:
+ * 
+ * <pre>
+ * Keyword = "select" | "set" | "from" | "at" | "as"
+ *         | "where" | "anywhere" | "like" | "unlike"
+ *         | "and" | "or" | "not" | "xor" | "with" | "infinity"
+ *         | "order" | "by" | "asc" | "desc";
+ * 
+ * Expression        = AddExpression;
+ * AddExpression     = MultExpression, [AddOperator, AddExpression];
+ * MultExpression    = BitwiseExpression, [MultOperator, MultExpression];
+ * BitwiseExpression = UnaryExpression, [BitwiseOperator, BitwiseExpression];
+ * UnaryExpression   = [UnaryOperator], (ParExpression | AtomicExpression);
+ * AtomicExpression  = FunctionCall | Identifier | Literal;
+ * ParExpression     = "(", Expression, ")";
+ * 
+ * BitwiseOperator = "&" | "|" | "^";
+ * MultOperator    = "*" | "/";
+ * AddOperator     = "+" | "-";
+ * UnaryOperator   = "+" | "-" | "~";
+ * 
+ * FunctionCall    = Identifier, "(", [ArgumentList], ")";
+ * ArgumentList    = Expression, {",", Expression};
+ * Identifier      = IdentifierChar - ?Digit?, {IdentifierChar}
+ *                 | "`", ?Character? - "`", {?Character? - "`"}, "`";
+ * IdentifierChar  = ?Character? - (" "|",");
+ * Literal         = Number | String | Timestamp;
+ * Number          = ?Digit?, {?Digit?} | "%d";
+ * String          = "'", {?Character? - "'" | "'''"} , "'" | "%s";
+ * Timestamp       = "%t"; // TODO: maybe introduce a real literal 
+ * 
+ * LogicalExpression = BooleanExpression, [LogicalOperator, LogicalExpression];
+ * BooleanExpression = "not ", BooleanExpression
+ *                   | "(", LogicalExpression, ")"
+ *                   | BooleanPrimary;
+ * BooleanPrimary    = Expression, (" like " | " unlike "), String
+ *                   | Expression, Comparison, Expression
+ *                   | FunctionCall | Identifier;
+ * 
+ * LogicalOperator = " and " | " or " | " xor ";
+ * Comparison      = | "=" | "<" | ">" | "<=" | ">=" | "!=";
+ * 
+ * FieldExpressions = "-"
+ *                  | "*", {",", NamedField}
+ *                  | FieldExpression, {",", FieldExpression};
+ * FieldExpression  = NamedField | Identifier;
+ * NamedField       = Expression, " as ", Identifier;
+ * 
+ * Assignments   = Assignment, {",", Assignment};
+ * Assignment    = Identifier, "=", Expression;
+ * 
+ * Path     = String
+ *          | "/", [PathNode, {"/", PathNode}], ["/"];
+ * PathNode = {{?Character? - "/"} - Keyword};
+ * 
+ * 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, identifier or the path.
+ * 
+ * <b>SELECT:</b>
+ * <pre>
+ * SelectStatement = "select ", FieldExpressions,
+ * " from ", Path,
+ * [" with ", WithClause],
+ * [(" where ", LogicalExpression) | " anywhere"],
+ * [" order by ", OrderByClause];
+  * </pre>
+ * 
+ * <b>SET:</b>
+ * <pre>
+ * SetStatement = "set ",Assignments,
+ * " at ", Path,
+ * [" with ", WithClause],
+ * (" where ", LogicalExpression) | " anywhere";
+ * </pre>
+ * 
+ */
+typedef struct {
+    /**
+     * The original query text.
+     */
+    cxstring 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 DavQLFields.
+     */
+    CxList* fields;
+    /**
+     * A string that denotes the queried path.
+     */
+    cxstring path;
+    /**
+     * Logical expression for selection.
+     * <code>NULL</code>, if there is no where clause.
+     */
+    DavQLExpression* where;
+    /**
+     * The list of DavQLOrderCriterions.
+     * This is <code>NULL</code> for SET queries and may be <code>NULL</code>
+     * if the result doesn't need to be sorted.
+     */
+    CxList* orderby;
+    /**
+     * The recursion depth for the statement.
+     * Defaults to 1.
+     * Magic numbers are DAV_DEPTH_INFINITY for infinity and
+     * DAV_DEPTH_PLACEHOLDER for a placeholder.
+     */
+    int depth;
+    /**
+     * A list of all required arguments
+     */
+    CxList* args;
+} DavQLStatement;
+
+/** Infinity recursion depth for a DavQLStatement. */
+#define DAV_DEPTH_INFINITY -1
+
+/** Depth needs to be specified at runtime. */
+#define DAV_DEPTH_PLACEHOLDER -2
+
+/** Unexpected token. */
+#define DAVQL_ERROR_UNEXPECTED_TOKEN 1
+
+/** A token has been found, for which no token class is applicable. */
+#define DAVQL_ERROR_INVALID_TOKEN 2
+
+/** A token that has been expected was not found. */
+#define DAVQL_ERROR_MISSING_TOKEN 11
+
+/** An expression has been expected, but was not found. */
+#define DAVQL_ERROR_MISSING_EXPR 12
+
+/** A closed parenthesis ')' is missing. */
+#define DAVQL_ERROR_MISSING_PAR 13
+
+/** An assignment operator '=' is missing. */
+#define DAVQL_ERROR_MISSING_ASSIGN 14
+
+/** The type of the expression could not be determined. */
+#define DAVQL_ERROR_INVALID_EXPR 21
+
+/** An operator has been found for an unary expression, but it is invalid. */
+#define DAVQL_ERROR_INVALID_UNARY_OP 22
+
+/** An operator has been found for a logical expression, but it is invalid. */
+#define DAVQL_ERROR_INVALID_LOGICAL_OP 23
+
+/** Invalid format specifier. */
+#define DAVQL_ERROR_INVALID_FMTSPEC 24
+
+/** A string has been expected. */
+#define DAVQL_ERROR_INVALID_STRING 25
+
+/** The order criterion is invalid (must be an identifier or field index). */
+#define DAVQL_ERROR_INVALID_ORDER_CRITERION 26
+
+/** The depth is invalid. */
+#define DAVQL_ERROR_INVALID_DEPTH 101
+
+/** Nothing about the statement seems legit. */
+#define DAVQL_ERROR_INVALID -1
+
+/** A call to malloc or calloc failed. */
+#define DAVQL_ERROR_OUT_OF_MEMORY -2
+
+/**
+ * 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(cxstring stmt);
+
+/**
+ * Implicitly converts a cstr to a sstr_t and calls dav_parse_statement.
+ */
+#define dav_parse_cstr_statement(stmt) dav_parse_statement(cx_str(stmt))
+
+/**
+ * Frees a DavQLStatement.
+ * @param stmt the statement object to free
+ */
+void dav_free_statement(DavQLStatement *stmt);
+
+#ifdef	__cplusplus
+}
+#endif
+
+#endif	/* DAVQLPARSER_H */
+