![[tokkee]](http://tokkee.org/images/avatar.png){kind=avatar}
diff --git a/src/include/parser/ast.h b/src/include/parser/ast.h
--- /dev/null
+++ b/src/include/parser/ast.h
@@ -0,0 +1,380 @@
+/*
+ * SysDB - src/include/parser/ast.h
+ * Copyright (C) 2013-2015 Sebastian 'tokkee' Harl <sh@tokkee.org>
+ * 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 HOLDERS 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.
+ */
+
+/*
+ * The SysDB query language AST describes the parse-tree of an SysQL query.
+ */
+
+#ifndef SDB_PARSER_AST_H
+#define SDB_PARSER_AST_H 1
+
+#include "core/data.h"
+#include "core/time.h"
+#include "core/object.h"
+
+#include <assert.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * sdb_ast_node_type_t describes the type of an AST node.
+ */
+typedef enum {
+ /* command nodes */
+ SDB_AST_TYPE_FETCH = 1,
+ SDB_AST_TYPE_LIST = 2,
+ SDB_AST_TYPE_LOOKUP = 3,
+ SDB_AST_TYPE_STORE = 4,
+ SDB_AST_TYPE_TIMESERIES = 5,
+
+ /* generic expressions */
+ SDB_AST_TYPE_OPERATOR = 100,
+ SDB_AST_TYPE_ITERATOR = 101,
+
+ /* values */
+ SDB_AST_TYPE_CONST = 200,
+ SDB_AST_TYPE_VALUE = 201,
+
+ SDB_AST_TYPE_TYPED = 210,
+} sdb_ast_node_type_t;
+
+/*
+ * sdb_ast_operator_t describes the type of an operator.
+ */
+typedef enum {
+ /* logical and comparison operators */
+#define SDB_AST_IS_LOGICAL(n) \
+ ((((n)->type == SDB_AST_TYPE_OPERATOR) \
+ && ((SDB_AST_AND <= SDB_AST_OP(n)->kind) \
+ && (SDB_AST_OP(n)->kind <= SDB_AST_IN))) \
+ || (((n)->type == SDB_AST_TYPE_ITERATOR) \
+ && ((SDB_AST_ALL <= SDB_AST_ITER(n)->kind) \
+ && (SDB_AST_ITER(n)->kind <= SDB_AST_ANY))))
+ SDB_AST_AND = 1000,
+ SDB_AST_OR = 1001,
+ SDB_AST_NOT = 1002,
+
+ SDB_AST_LT = 1010,
+ SDB_AST_LE = 1011,
+ SDB_AST_EQ = 1012,
+ SDB_AST_NE = 1013,
+ SDB_AST_GE = 1014,
+ SDB_AST_GT = 1015,
+ SDB_AST_REGEX = 1016,
+ SDB_AST_NREGEX = 1017,
+ SDB_AST_ISNULL = 1018,
+ SDB_AST_IN = 1019,
+
+ /* arithmetic expressions */
+#define SDB_AST_IS_ARITHMETIC(n) \
+ (((n)->type == SDB_AST_TYPE_CONST) \
+ || ((n)->type == SDB_AST_TYPE_VALUE) \
+ || ((n)->type == SDB_AST_TYPE_TYPED) \
+ || (((n)->type == SDB_AST_TYPE_OPERATOR) \
+ && ((SDB_AST_ADD <= SDB_AST_OP(n)->kind) \
+ && (SDB_AST_OP(n)->kind <= SDB_AST_CONCAT))))
+ SDB_AST_ADD = 2000,
+ SDB_AST_SUB = 2001,
+ SDB_AST_MUL = 2002,
+ SDB_AST_DIV = 2003,
+ SDB_AST_MOD = 2004,
+ SDB_AST_CONCAT = 2005,
+
+ /* iterators */
+ SDB_AST_ALL = 3000,
+ SDB_AST_ANY = 3001,
+} sdb_ast_operator_t;
+
+#define SDB_AST_OP_TO_STRING(op) \
+ (((op) == SDB_AST_AND) ? "AND" \
+ : ((op) == SDB_AST_OR) ? "OR" \
+ : ((op) == SDB_AST_NOT) ? "NOT" \
+ : ((op) == SDB_AST_LT) ? "LT" \
+ : ((op) == SDB_AST_LE) ? "LE" \
+ : ((op) == SDB_AST_EQ) ? "EQ" \
+ : ((op) == SDB_AST_NE) ? "NE" \
+ : ((op) == SDB_AST_GE) ? "GE" \
+ : ((op) == SDB_AST_GT) ? "GT" \
+ : ((op) == SDB_AST_REGEX) ? "REGEX" \
+ : ((op) == SDB_AST_NREGEX) ? "NREGEX" \
+ : ((op) == SDB_AST_ISNULL) ? "ISNULL" \
+ : ((op) == SDB_AST_IN) ? "IN" \
+ : ((op) == SDB_AST_ADD) ? "ADD" \
+ : ((op) == SDB_AST_SUB) ? "SUB" \
+ : ((op) == SDB_AST_MUL) ? "MUL" \
+ : ((op) == SDB_AST_DIV) ? "DIV" \
+ : ((op) == SDB_AST_MOD) ? "MOD" \
+ : ((op) == SDB_AST_CONCAT) ? "CONCAT" \
+ : ((op) == SDB_AST_ALL) ? "ALL" \
+ : ((op) == SDB_AST_ANY) ? "ANY" \
+ : "UNKNOWN")
+
+/*
+ * sdb_ast_node_t is the interface for AST nodes. The first field of any
+ * actual implementation of the interface is of type sdb_ast_node_t to
+ * fascilitate casting between the interface and implementation types.
+ *
+ * It inherits from sdb_object_t and instances may safely be cast to a generic
+ * object as well.
+ */
+typedef struct {
+ sdb_object_t super;
+
+ /* type describes the type of the actual node */
+ int type;
+} sdb_ast_node_t;
+#define SDB_AST_NODE(obj) ((sdb_ast_node_t *)(obj))
+
+/*
+ * sdb_ast_op_t represents a simple operation.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ int kind;
+ /* left operand is NULL for unary expressions */
+ sdb_ast_node_t *left;
+ sdb_ast_node_t *right;
+} sdb_ast_op_t;
+#define SDB_AST_OP(obj) ((sdb_ast_op_t *)(obj))
+
+/*
+ * sdb_ast_iter_t represents an iterator.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ int kind;
+ int op;
+ sdb_ast_node_t *iter;
+ /* exactly one operand of the expression has to be unset and will be
+ * filled in by the iterator value */
+ sdb_ast_node_t *expr;
+} sdb_ast_iter_t;
+#define SDB_AST_ITER(obj) ((sdb_ast_iter_t *)(obj))
+
+/*
+ * sdb_ast_typed_t represents a typed value.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ int type;
+ sdb_ast_node_t *expr;
+} sdb_ast_typed_t;
+#define SDB_AST_TYPED(obj) ((sdb_ast_typed_t *)(obj))
+
+/*
+ * sdb_ast_const_t represents a constant value.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ sdb_data_t value;
+} sdb_ast_const_t;
+#define SDB_AST_CONST(obj) ((sdb_ast_const_t *)(obj))
+
+/*
+ * sdb_ast_value_t represents an object-specific value: sibling nodes,
+ * attributes, or field values.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ int type; /* attribute or field */
+ char *name; /* object name; optional */
+} sdb_ast_value_t;
+#define SDB_AST_VALUE(obj) ((sdb_ast_value_t *)(obj))
+
+/*
+ * sdb_ast_fetch_t represents a FETCH command.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ int obj_type;
+ char *hostname; /* optional */
+ char *name;
+ sdb_ast_node_t *filter; /* optional */
+} sdb_ast_fetch_t;
+#define SDB_AST_FETCH(obj) ((sdb_ast_fetch_t *)(obj))
+
+/*
+ * sdb_ast_list_t represents a LIST command.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ int obj_type;
+ sdb_ast_node_t *filter; /* optional */
+} sdb_ast_list_t;
+#define SDB_AST_LIST(obj) ((sdb_ast_list_t *)(obj))
+
+/*
+ * sdb_ast_lookup_t represents a LOOKUP command.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ int obj_type;
+ sdb_ast_node_t *matcher; /* optional */
+ sdb_ast_node_t *filter; /* optional */
+} sdb_ast_lookup_t;
+#define SDB_AST_LOOKUP(obj) ((sdb_ast_lookup_t *)(obj))
+
+/*
+ * sdb_ast_store_t represents a STORE command.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ int obj_type;
+ char *hostname; /* optional */
+ int parent_type; /* optional */
+ char *parent; /* optional */
+ char *name;
+ sdb_time_t last_update;
+
+ /* metric specific */
+ char *store_type;
+ char *store_id;
+
+ /* attribute specific */
+ sdb_data_t value;
+} sdb_ast_store_t;
+#define SDB_AST_STORE(obj) ((sdb_ast_store_t *)(obj))
+
+/*
+ * sdb_ast_timeseries_t represents a TIMESERIES command.
+ */
+typedef struct {
+ sdb_ast_node_t super;
+ char *hostname;
+ char *metric;
+ sdb_time_t start;
+ sdb_time_t end;
+} sdb_ast_timeseries_t;
+#define SDB_AST_TIMESERIES(obj) ((sdb_ast_timeseries_t *)(obj))
+
+/*
+ * AST constructors:
+ * Newly created nodes take ownership of any dynamically allocated objects
+ * (node objects, dynamically allocated constant values, strings). The memory
+ * will be freed when destroying the node using sdb_object_deref.
+ *
+ * The constructors do not verify any arguments. The analyzer has to be used
+ * for that purpose.
+ */
+
+/*
+ * sdb_ast_op_create:
+ * Creates an AST node representing a simple (ary or unary) operation. The
+ * newly created node takes ownership of the left and right nodes.
+ */
+sdb_ast_node_t *
+sdb_ast_op_create(int kind, sdb_ast_node_t *left, sdb_ast_node_t *right);
+
+/*
+ * sdb_ast_iter_create:
+ * Creates an AST node representing an iterator. The newly created node takes
+ * ownership of the iter and expr nodes.
+ */
+sdb_ast_node_t *
+sdb_ast_iter_create(int kind, int op,
+ sdb_ast_node_t *iter, sdb_ast_node_t *expr);
+
+/*
+ * sdb_ast_typed_create:
+ * Creates an AST node representing a typed expression. Thew newly created
+ * node takes ownership of the expr node.
+ */
+sdb_ast_node_t *
+sdb_ast_typed_create(int type, sdb_ast_node_t *expr);
+
+/*
+ * sdb_ast_const_create:
+ * Creates an AST node representing a constant value. The newly created node
+ * takes ownership of the value object.
+ */
+sdb_ast_node_t *
+sdb_ast_const_create(sdb_data_t value);
+
+/*
+ * sdb_ast_value_create:
+ * Creates an AST node representing an object-specific value (sibling nodes,
+ * attributes, or field values). The newly created node takes ownership of the
+ * string value.
+ */
+sdb_ast_node_t *
+sdb_ast_value_create(int type, char *name);
+
+/*
+ * sdb_ast_fetch_create:
+ * Creates an AST node representing a FETCH command. The newly created node
+ * takes ownership of the strings and the filter node.
+ */
+sdb_ast_node_t *
+sdb_ast_fetch_create(int obj_type, char *hostname, char *name,
+ sdb_ast_node_t *filter);
+
+/*
+ * sdb_ast_list_create:
+ * Creates an AST node representing a LIST command. The newly created node
+ * takes ownership of the filter node.
+ */
+sdb_ast_node_t *
+sdb_ast_list_create(int obj_type, sdb_ast_node_t *filter);
+
+/*
+ * sdb_ast_lookup_create:
+ * Creates an AST node representing a LOOKUP command. The newly created node
+ * takes ownership of the matcher and filter nodes.
+ */
+sdb_ast_node_t *
+sdb_ast_lookup_create(int obj_type, sdb_ast_node_t *matcher,
+ sdb_ast_node_t *filter);
+
+/*
+ * sdb_ast_store_create:
+ * Creates an AST node representing a STORE command. Thew newly created node
+ * takes ownership of all strings and the value object.
+ */
+sdb_ast_node_t *
+sdb_ast_store_create(int obj_type, char *hostname,
+ int parent_type, char *parent, char *name, sdb_time_t last_update,
+ char *store_type, char *store_id, sdb_data_t value);
+
+/*
+ * sdb_ast_timeseries_create:
+ * Creates an AST node representing a TIMESERIES command. The newly created
+ * node takes ownership of the strings.
+ */
+sdb_ast_node_t *
+sdb_ast_timeseries_create(char *hostname, char *metric,
+ sdb_time_t start, sdb_time_t end);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* ! SDB_PARSER_AST_H */
+
+/* vim: set tw=78 sw=4 ts=4 noexpandtab : */
+