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Diffstat (limited to 'indra/llcommon/llpredicate.h')
| -rw-r--r-- | indra/llcommon/llpredicate.h | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/indra/llcommon/llpredicate.h b/indra/llcommon/llpredicate.h new file mode 100644 index 0000000000..a0e970a799 --- /dev/null +++ b/indra/llcommon/llpredicate.h @@ -0,0 +1,210 @@ +/** + * @file llpredicate.h + * @brief abstraction for filtering objects by predicates, with arbitrary boolean expressions + * + * $LicenseInfo:firstyear=2008&license=viewerlgpl$ + * Second Life Viewer Source Code + * Copyright (C) 2010, Linden Research, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; + * version 2.1 of the License only. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + * + * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA + * $/LicenseInfo$ + */ + +#ifndef LL_LLPREDICATE_H +#define LL_LLPREDICATE_H + +#include "llerror.h" + +namespace LLPredicate +{ + template<typename ENUM> class Rule; + + extern const U32 cPredicateFlagsFromEnum[5]; + + template<typename ENUM> + class Value + { + public: + typedef U32 predicate_flag_t; + static const S32 cMaxEnum = 5; + + Value(ENUM e, bool predicate_value = true) + : mPredicateFlags(predicate_value ? cPredicateFlagsFromEnum[e] : ~cPredicateFlagsFromEnum[e]) + { + llassert(0 <= e && e < cMaxEnum); + } + + Value() + : mPredicateFlags(0xFFFFffff) + {} + + Value operator!() const + { + Value new_value; + new_value.mPredicateFlags = ~mPredicateFlags; + return new_value; + } + + Value operator &&(const Value other) const + { + Value new_value; + new_value.mPredicateFlags = mPredicateFlags & other.mPredicateFlags; + return new_value; + } + + Value operator ||(const Value other) const + { + Value new_value; + new_value.mPredicateFlags = mPredicateFlags | other.mPredicateFlags; + return new_value; + } + + void set(ENUM e, bool value = true) + { + llassert(0 <= e && e < cMaxEnum); + predicate_flag_t flags_to_modify; + predicate_flag_t mask = cPredicateFlagsFromEnum[e]; + if (value) + { // add predicate "e" to flags that don't contain it already + flags_to_modify = (mPredicateFlags & ~mask); + // clear flags not containing e + mPredicateFlags &= mask; + // add back flags shifted to contain e + mPredicateFlags |= flags_to_modify << (0x1 << e); + } + else + { // remove predicate "e" from flags that contain it + flags_to_modify = (mPredicateFlags & mask); + // clear flags containing e + mPredicateFlags &= ~mask; + // add back flags shifted to not contain e + mPredicateFlags |= flags_to_modify >> (0x1 << e); + } + } + + void forget(ENUM e) + { + set(e, true); + U32 flags_with_predicate = mPredicateFlags; + set(e, false); + // ambiguous value is result of adding and removing predicate at the same time! + mPredicateFlags |= flags_with_predicate; + } + + bool allSet() const + { + return mPredicateFlags == ~0; + } + + bool noneSet() const + { + return mPredicateFlags == 0; + } + + bool someSet() const + { + return mPredicateFlags != 0; + } + + private: + predicate_flag_t mPredicateFlags; + }; + + template<typename ENUM> + class Rule + { + public: + Rule(ENUM value) + : mRule(value) + {} + + Rule(const Value<ENUM> other) + : mRule(other) + {} + + Rule() + {} + + void require(ENUM e) + { + mRule.set(e, require); + } + + void allow(ENUM e) + { + mRule.forget(e); + } + + bool check(const Value<ENUM> value) const + { + return (mRule && value).someSet(); + } + + bool requires(const Value<ENUM> value) const + { + return (mRule && value).someSet() && (!mRule && value).noneSet(); + } + + bool isAmbivalent(const Value<ENUM> value) const + { + return (mRule && value).someSet() && (!mRule && value).someSet(); + } + + bool acceptsAll() const + { + return mRule.allSet(); + } + + bool acceptsNone() const + { + return mRule.noneSet(); + } + + Rule operator!() const + { + Rule new_rule; + new_rule.mRule = !mRule; + return new_rule; + } + + Rule operator &&(const Rule other) const + { + Rule new_rule; + new_rule.mRule = mRule && other.mRule; + return new_rule; + } + + Rule operator ||(const Rule other) const + { + Rule new_rule; + new_rule.mRule = mRule || other.mRule; + return new_rule; + } + + private: + Value<ENUM> mRule; + }; +} + +template<typename ENUM> +LLPredicate::Value<ENUM> ll_make_predicate(ENUM e, bool predicate_value = true) +{ + return LLPredicate::Value<ENUM>(e, predicate_value); +} + + +#endif // LL_LLPREDICATE_H |