diff options
| -rw-r--r-- | CHANGELOG.md | 4 | ||||
| -rw-r--r-- | doc/concepts/expressions.md | 5 | ||||
| -rw-r--r-- | src/buildtool/build_engine/expression/evaluator.cpp | 30 | ||||
| -rw-r--r-- | test/buildtool/build_engine/expression/expression.test.cpp | 13 |
4 files changed, 50 insertions, 2 deletions
diff --git a/CHANGELOG.md b/CHANGELOG.md index 56709f0f..22581d9e 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -21,8 +21,8 @@ A feature release on top of `1.3.0`, backwards compatible. at the old location will not be used anymore while still using disk space. - The expression language has been extended to contain quote and - quasi-quote expressions, as well as a new built-in function - `"from_subdir"`. + quasi-quote expressions, as well as new built-in functions + `"from_subdir"`, `"nub_left"`. ### Fixes diff --git a/doc/concepts/expressions.md b/doc/concepts/expressions.md index c75f00dc..4db7c8cb 100644 --- a/doc/concepts/expressions.md +++ b/doc/concepts/expressions.md @@ -248,6 +248,11 @@ those) argument(s) to obtain the final result. result is the input list, except that for all duplicate values, all but the rightmost occurrence is removed. + - `"nub_list"` The argument has to be a list. It is an error + if that list contains (directly or indirectly) a name. The + result is the input list, except that for all duplicate + values, all but the leftmost occurrence is removed. + - `"basename"` The argument has to be a string. This string is interpreted as a path, and the file name thereof is returned. diff --git a/src/buildtool/build_engine/expression/evaluator.cpp b/src/buildtool/build_engine/expression/evaluator.cpp index e2b3819d..350afa4e 100644 --- a/src/buildtool/build_engine/expression/evaluator.cpp +++ b/src/buildtool/build_engine/expression/evaluator.cpp @@ -279,6 +279,35 @@ auto NubRight(ExpressionPtr const& expr) -> ExpressionPtr { return ExpressionPtr{reverse_result}; } +auto NubLeft(ExpressionPtr const& expr) -> ExpressionPtr { + if (not expr->IsList()) { + throw Evaluator::EvaluationError{fmt::format( + "nub_left expects list but instead got: {}.", expr->ToString())}; + } + if (not expr->IsCacheable()) { + throw Evaluator::EvaluationError{ + fmt::format("Implicit comparison by passing name-containing value " + "to nub_left: {}", + expr->ToString())}; + } + // short-cut evaluation for efficiency + if (expr->List().empty()) { + return expr; + } + auto const& list = expr->List(); + auto result = Expression::list_t{}; + result.reserve(list.size()); + auto seen = std::unordered_set<ExpressionPtr>{}; + seen.reserve(list.size()); + std::for_each(list.begin(), list.end(), [&](auto const& l) { + if (not seen.contains(l)) { + result.push_back(l); + seen.insert(l); + } + }); + return ExpressionPtr{result}; +} + auto Range(ExpressionPtr const& expr) -> ExpressionPtr { std::size_t len = 0; if (expr->IsNumber() && expr->Number() > 0.0) { @@ -1263,6 +1292,7 @@ auto const kBuiltInFunctions = {"+", UnaryExpr(Addition)}, {"*", UnaryExpr(Multiplication)}, {"nub_right", UnaryExpr(NubRight)}, + {"nub_left", UnaryExpr(NubLeft)}, {"range", UnaryExpr(Range)}, {"change_ending", ChangeEndingExpr}, {"basename", UnaryExpr(BaseName)}, diff --git a/test/buildtool/build_engine/expression/expression.test.cpp b/test/buildtool/build_engine/expression/expression.test.cpp index 938bd63f..83d6a2fe 100644 --- a/test/buildtool/build_engine/expression/expression.test.cpp +++ b/test/buildtool/build_engine/expression/expression.test.cpp @@ -946,6 +946,19 @@ TEST_CASE("Expression Evaluation", "[expression]") { // NOLINT )"_json)); } + SECTION("nub_left expression") { + auto expr = Expression::FromJson(R"( + {"type": "nub_left" + , "$1": ["a", "b", "b", "a", "c", "b", "a"] + })"_json); + REQUIRE(expr); + + auto result = expr.Evaluate(env, fcts); + REQUIRE(result); + REQUIRE(result->IsList()); + CHECK(result == Expression::FromJson(R"(["a", "b", "c"])"_json)); + } + SECTION("change_ending") { auto expr = Expression::FromJson(R"( { "type": "change_ending" |