I've been saying for a while[1][2][3] that adding extra abstractions makes things harder for newcomers, and adding new notations doubly so. And then I notice this DSL in my own backyard. Makes me feel like a hypocrite. [1] https://news.ycombinator.com/item?id=13565743#13570092 [2] https://lobste.rs/s/to8wpr/configuration_files_are_canary_warning [3] https://lobste.rs/s/mdmcdi/little_languages_by_jon_bentley_1986#c_3miuf2 The implementation of the DSL was also highly hacky: a) It was happening in the tangle/ tool, but was utterly unrelated to tangling layers. b) There were several persnickety constraints on the different kinds of lines and the specific order they were expected in. I kept finding bugs where the translator would silently do the wrong thing. Or the error messages sucked, and readers may be stuck looking at the generated code to figure out what happened. Fixing error messages would require a lot more code, which is one of my arguments against DSLs in the first place: they may be easy to implement, but they're hard to design to go with the grain of the underlying platform. They require lots of iteration. Is that effort worth prioritizing in this project? On the other hand, the DSL did make at least some readers' life easier, the ones who weren't immediately put off by having to learn a strange syntax. There were fewer quotes to parse, fewer backslash escapes. Anyway, since there are also people who dislike having to put up with strange syntaxes, we'll call that consideration a wash and tear this DSL out. --- This commit was sheer drudgery. Hopefully it won't need to be redone with a new DSL because I grow sick of backslashes.
261 lines
8.0 KiB
C++
261 lines
8.0 KiB
C++
//: Introduce a new transform to perform various checks in instructions before
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//: we start running them. It'll be extensible, so that we can add checks for
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//: new recipes as we extend 'run' to support them.
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//:
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//: Doing checking in a separate part complicates things, because the values
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//: of variables in memory and the processor (current_recipe_name,
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//: current_instruction) aren't available at checking time. If I had a more
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//: sophisticated layer system I'd introduce the simpler version first and
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//: transform it in a separate layer or set of layers.
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:(before "End Checks")
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Transform.push_back(check_instruction); // idempotent
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:(code)
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void check_instruction(const recipe_ordinal r) {
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trace(101, "transform") << "--- perform checks for recipe " << get(Recipe, r).name << end();
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map<string, vector<type_ordinal> > metadata;
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for (int i = 0; i < SIZE(get(Recipe, r).steps); ++i) {
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instruction& inst = get(Recipe, r).steps.at(i);
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if (inst.is_label) continue;
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switch (inst.operation) {
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// Primitive Recipe Checks
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case COPY: {
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if (SIZE(inst.products) > SIZE(inst.ingredients)) {
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raise << maybe(get(Recipe, r).name) << "too many products in '" << to_original_string(inst) << "'\n" << end();
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break;
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}
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for (int i = 0; i < SIZE(inst.products); ++i) {
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if (!types_coercible(inst.products.at(i), inst.ingredients.at(i))) {
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raise << maybe(get(Recipe, r).name) << "can't copy '" << inst.ingredients.at(i).original_string << "' to '" << inst.products.at(i).original_string << "'; types don't match\n" << end();
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goto finish_checking_instruction;
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}
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}
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break;
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}
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// End Primitive Recipe Checks
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default: {
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// Defined Recipe Checks
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// End Defined Recipe Checks
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}
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}
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finish_checking_instruction:;
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}
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}
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void test_copy_checks_reagent_count() {
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Hide_errors = true;
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run(
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"def main [\n"
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" 1:num, 2:num <- copy 34\n"
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"]\n"
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);
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CHECK_TRACE_CONTENTS(
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"error: main: too many products in '1:num, 2:num <- copy 34'\n"
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);
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}
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void test_write_scalar_to_array_disallowed() {
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Hide_errors = true;
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run(
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"def main [\n"
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" 1:array:num <- copy 34\n"
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"]\n"
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);
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CHECK_TRACE_CONTENTS(
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"error: main: can't copy '34' to '1:array:num'; types don't match\n"
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);
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}
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void test_write_scalar_to_array_disallowed_2() {
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Hide_errors = true;
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run(
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"def main [\n"
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" 1:num, 2:array:num <- copy 34, 35\n"
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"]\n"
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);
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CHECK_TRACE_CONTENTS(
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"error: main: can't copy '35' to '2:array:num'; types don't match\n"
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);
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}
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void test_write_scalar_to_address_disallowed() {
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Hide_errors = true;
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run(
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"def main [\n"
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" 1:&:num <- copy 34\n"
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"]\n"
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);
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CHECK_TRACE_CONTENTS(
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"error: main: can't copy '34' to '1:&:num'; types don't match\n"
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);
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}
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void test_write_address_to_character_disallowed() {
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Hide_errors = true;
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run(
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"def main [\n"
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" 1:&:num <- copy 12/unsafe\n"
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" 2:char <- copy 1:&:num\n"
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"]\n"
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);
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CHECK_TRACE_CONTENTS(
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"error: main: can't copy '1:&:num' to '2:char'; types don't match\n"
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);
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}
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void test_write_number_to_character_allowed() {
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run(
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"def main [\n"
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" 1:num <- copy 97\n"
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" 2:char <- copy 1:num\n"
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"]\n"
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);
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CHECK_TRACE_COUNT("error", 0);
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}
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:(code)
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// types_match with some leniency
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bool types_coercible(reagent/*copy*/ to, reagent/*copy*/ from) {
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// Begin types_coercible(reagent to, reagent from)
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if (types_match_sub(to, from)) return true;
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if (is_real_mu_number(from) && is_mu_character(to)) return true;
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// End types_coercible Special-cases
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return false;
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}
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bool types_match_sub(const reagent& to, const reagent& from) {
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// to sidestep type-checking, use /unsafe in the source.
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// this will be highlighted in red inside vim. just for setting up some tests.
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if (is_unsafe(from)) return true;
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if (is_literal(from)) {
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if (is_mu_array(to)) return false;
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// End Matching Types For Literal(to)
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if (!to.type) return false;
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// allow writing null to any address
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if (is_mu_address(to)) return from.name == "null";
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return size_of(to) == 1; // literals are always scalars
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}
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return types_strictly_match_sub(to, from);
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}
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// variant for others to call
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bool types_match(reagent/*copy*/ to, reagent/*copy*/ from) {
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// Begin types_match(reagent to, reagent from)
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return types_match_sub(to, from);
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}
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//: copy arguments for later layers
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bool types_strictly_match_sub(const reagent& to, const reagent& from) {
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if (to.type == NULL) return false; // error
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if (is_literal(from) && to.type->value == Number_type_ordinal) return true;
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// to sidestep type-checking, use /unsafe in the source.
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// this will be highlighted in red inside vim. just for setting up some tests.
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if (is_unsafe(from)) return true;
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// '_' never raises type error
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if (is_dummy(to)) return true;
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if (!to.type) return !from.type;
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return types_strictly_match(to.type, from.type);
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}
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// variant for others to call
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bool types_strictly_match(reagent/*copy*/ to, reagent/*copy*/ from) {
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// Begin types_strictly_match(reagent to, reagent from)
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return types_strictly_match_sub(to, from);
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}
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bool types_strictly_match(const type_tree* to, const type_tree* from) {
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if (from == to) return true;
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if (!to) return false;
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if (!from) return to->atom && to->value == 0;
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if (from->atom != to->atom) return false;
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if (from->atom) {
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if (from->value == -1) return from->name == to->name;
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return from->value == to->value;
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}
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if (types_strictly_match(to->left, from->left) && types_strictly_match(to->right, from->right))
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return true;
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// fallback: (x) == x
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if (to->right == NULL && types_strictly_match(to->left, from)) return true;
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if (from->right == NULL && types_strictly_match(to, from->left)) return true;
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return false;
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}
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void test_unknown_type_does_not_match_unknown_type() {
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reagent a("a:foo");
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reagent b("b:bar");
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CHECK(!types_strictly_match(a, b));
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}
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void test_unknown_type_matches_itself() {
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reagent a("a:foo");
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reagent b("b:foo");
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CHECK(types_strictly_match(a, b));
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}
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void test_type_abbreviations_match_raw_types() {
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put(Type_abbreviations, "text", new_type_tree("address:array:character"));
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// a has type (address buffer (address array character))
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reagent a("a:address:buffer:text");
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expand_type_abbreviations(a.type);
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// b has type (address buffer address array character)
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reagent b("b:address:buffer:address:array:character");
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CHECK(types_strictly_match(a, b));
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delete Type_abbreviations["text"];
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put(Type_abbreviations, "text", NULL);
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}
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//: helpers
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bool is_unsafe(const reagent& r) {
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return has_property(r, "unsafe");
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}
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bool is_mu_array(reagent/*copy*/ r) {
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// End Preprocess is_mu_array(reagent r)
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return is_mu_array(r.type);
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}
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bool is_mu_array(const type_tree* type) {
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if (!type) return false;
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if (is_literal(type)) return false;
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if (type->atom) return false;
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if (!type->left->atom) {
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raise << "invalid type " << to_string(type) << '\n' << end();
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return false;
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}
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return type->left->value == Array_type_ordinal;
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}
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bool is_mu_boolean(reagent/*copy*/ r) {
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// End Preprocess is_mu_boolean(reagent r)
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if (!r.type) return false;
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if (is_literal(r)) return false;
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if (!r.type->atom) return false;
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return r.type->value == Boolean_type_ordinal;
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}
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bool is_mu_number(reagent/*copy*/ r) {
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if (is_mu_character(r.type)) return true; // permit arithmetic on unicode code points
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return is_real_mu_number(r);
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}
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bool is_real_mu_number(reagent/*copy*/ r) {
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// End Preprocess is_mu_number(reagent r)
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if (!r.type) return false;
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if (!r.type->atom) return false;
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if (is_literal(r)) {
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return r.type->name == "literal-fractional-number"
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|| r.type->name == "literal";
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}
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return r.type->value == Number_type_ordinal;
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}
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bool is_mu_character(reagent/*copy*/ r) {
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// End Preprocess is_mu_character(reagent r)
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return is_mu_character(r.type);
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}
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bool is_mu_character(const type_tree* type) {
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if (!type) return false;
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if (!type->atom) return false;
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if (is_literal(type)) return false;
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return type->value == Character_type_ordinal;
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}
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