From: Sebastian Harl Date: Sun, 27 Jul 2014 22:25:16 +0000 (+0200) Subject: store_expr: Added framework for arithmetic expressions. X-Git-Tag: sysdb-0.3.0~26 X-Git-Url: https://git.tokkee.org/?p=sysdb.git;a=commitdiff_plain;h=bcdab455276ee24a4afb8d69db069c16d47f9b1e store_expr: Added framework for arithmetic expressions. A store expression describes the parse tree of an arithmetic expression and provides means to execute it (based on sdb_data_expr_eval()). --- diff --git a/src/Makefile.am b/src/Makefile.am index 2adc2e0..272533b 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -70,6 +70,7 @@ libsysdb_la_SOURCES = \ core/plugin.c include/core/plugin.h \ core/store.c include/core/store.h \ core/store-private.h \ + core/store_expr.c \ core/store_lookup.c \ core/data.c include/core/data.h \ frontend/connection.c include/frontend/connection.h \ diff --git a/src/core/store-private.h b/src/core/store-private.h index a2121f4..7479bc6 100644 --- a/src/core/store-private.h +++ b/src/core/store-private.h @@ -42,6 +42,10 @@ extern "C" { #endif +/* + * core types + */ + struct sdb_store_obj { sdb_object_t super; diff --git a/src/core/store_expr.c b/src/core/store_expr.c new file mode 100644 index 0000000..4d1fccb --- /dev/null +++ b/src/core/store_expr.c @@ -0,0 +1,155 @@ +/* + * SysDB - src/core/store_expr.c + * Copyright (C) 2014 Sebastian 'tokkee' Harl + * 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. + */ + +/* + * This module implements expressions which may be executed in the store. + */ + +#if HAVE_CONFIG_H +# include "config.h" +#endif /* HAVE_CONFIG_H */ + +#include "sysdb.h" +#include "core/store-private.h" +#include "core/object.h" + +#include + +/* + * private data types + */ + +struct sdb_store_expr { + sdb_object_t super; + + int type; + sdb_store_expr_t *left; + sdb_store_expr_t *right; + + sdb_data_t data; +}; + +/* + * private data types + */ + +static int +expr_init(sdb_object_t *obj, va_list ap) +{ + int type = va_arg(ap, int); + sdb_store_expr_t *left = va_arg(ap, sdb_store_expr_t *); + sdb_store_expr_t *right = va_arg(ap, sdb_store_expr_t *); + const sdb_data_t *value = va_arg(ap, const sdb_data_t *); + + sdb_store_expr_t *expr = SDB_STORE_EXPR(obj); + + if (! type) { + if (! value) + return -1; + } else { + if (value) + return -1; + if ((! left) || (! right)) + return -1; + } + + if (value) + if (sdb_data_copy(&expr->data, value)) + return -1; + + sdb_object_ref(SDB_OBJ(left)); + sdb_object_ref(SDB_OBJ(right)); + + expr->type = type; + expr->left = left; + expr->right = right; + return 0; +} /* expr_init */ + +static void +expr_destroy(sdb_object_t *obj) +{ + sdb_store_expr_t *expr = SDB_STORE_EXPR(obj); + sdb_object_deref(SDB_OBJ(expr->left)); + sdb_object_deref(SDB_OBJ(expr->right)); + + if (expr->data.type) + sdb_data_free_datum(&expr->data); +} /* expr_destroy */ + +static sdb_type_t expr_type = { + /* size = */ sizeof(sdb_store_expr_t), + /* init = */ expr_init, + /* destroy = */ expr_destroy, +}; + +/* + * public API + */ + +sdb_store_expr_t * +sdb_store_expr_create(int op, sdb_store_expr_t *left, sdb_store_expr_t *right) +{ + return SDB_STORE_EXPR(sdb_object_create("store-expr", expr_type, + op, left, right, NULL)); +} /* sdb_store_expr_create */ + +sdb_store_expr_t * +sdb_store_expr_constvalue(const sdb_data_t *value) +{ + return SDB_STORE_EXPR(sdb_object_create("store-constvalue", expr_type, + 0, NULL, NULL, value)); +} /* sdb_store_expr_constvalue */ + +int +sdb_store_expr_eval(sdb_store_expr_t *expr, sdb_data_t *res) +{ + sdb_data_t v1 = SDB_DATA_INIT, v2 = SDB_DATA_INIT; + + if ((! expr) || (! res)) + return -1; + + if (! expr->type) + return sdb_data_copy(res, &expr->data); + + if (sdb_store_expr_eval(expr->left, &v1)) + return -1; + if (sdb_store_expr_eval(expr->right, &v2)) { + sdb_data_free_datum(&v1); + return -1; + } + + if (sdb_data_expr_eval(expr->type, &v1, &v2, res)) { + sdb_data_free_datum(&v1); + sdb_data_free_datum(&v2); + return -1; + } + return 0; +} /* sdb_store_expr_eval */ + +/* vim: set tw=78 sw=4 ts=4 noexpandtab : */ + diff --git a/src/include/core/store.h b/src/include/core/store.h index 4e8d468..1b4e738 100644 --- a/src/include/core/store.h +++ b/src/include/core/store.h @@ -158,6 +158,52 @@ int sdb_store_service_attr(const char *hostname, const char *service, const char *key, const sdb_data_t *value, sdb_time_t last_update); +/* + * Expressions specify arithmetic expressions. + * + * A expression object inherits from sdb_object_t and, thus, may safely be + * cast to a generic object. + */ +struct sdb_store_expr; +typedef struct sdb_store_expr sdb_store_expr_t; +#define SDB_STORE_EXPR(obj) ((sdb_store_expr_t *)(obj)) + +/* + * sdb_store_expr_create: + * Creates an arithmetic expression implementing the specified operator on the + * specified left and right operand. + * + * Returns: + * - an expression object on success + * - NULL else + */ +sdb_store_expr_t * +sdb_store_expr_create(int op, sdb_store_expr_t *left, sdb_store_expr_t *right); + +/* + * sdb_store_expr_constvalue: + * Creates an expression which evaluates to the specified constant value. + * + * Returns: + * - an expression object on success + * - NULL else + */ +sdb_store_expr_t * +sdb_store_expr_constvalue(const sdb_data_t *value); + +/* + * sdb_store_expr_eval: + * Evaluate an expression and stores the result in 'res'. The result's value + * will be allocated dynamically if necessary and, thus, should be free'd by + * the caller (e.g. using sdb_data_free_datum); + * + * Returns: + * - 0 on success + * - a negative value else + */ +int +sdb_store_expr_eval(sdb_store_expr_t *expr, sdb_data_t *res); + /* * Conditionals may be used to lookup hosts from the store based on a * conditional expression.