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// This file defines how to compile reductions like `(+: nums)`
#include "../ast.h"
#include "../config.h"
#include "../environment.h"
#include "../stdlib/text.h"
#include "../stdlib/util.h"
#include "../typecheck.h"
#include "compilation.h"
public
Text_t compile_reduction(env_t *env, ast_t *ast) {
DeclareMatch(reduction, ast, Reduction);
ast_e op = reduction->op;
type_t *iter_t = get_type(env, reduction->iter);
type_t *item_t = get_iterated_type(iter_t);
if (!item_t)
code_err(reduction->iter, "I couldn't figure out how to iterate over this type: ", type_to_str(iter_t));
static int64_t next_id = 1;
ast_t *item = FakeAST(Var, String("$it", next_id++));
ast_t *body = LiteralCode(Text("{}")); // placeholder
ast_t *loop = FakeAST(For, .vars = new (ast_list_t, .ast = item), .iter = reduction->iter, .body = body);
env_t *body_scope = for_scope(env, loop);
if (op == Equals || op == NotEquals || op == LessThan || op == LessThanOrEquals || op == GreaterThan
|| op == GreaterThanOrEquals) {
// Chained comparisons like ==, <, etc.
type_t *item_value_type = item_t;
ast_t *item_value = item;
if (reduction->key) {
set_binding(body_scope, "$", item_t, compile(body_scope, item));
item_value = reduction->key;
item_value_type = get_type(body_scope, reduction->key);
}
Text_t code = Texts("({ // Reduction:\n", compile_declaration(item_value_type, Text("prev")),
";\n"
"OptionalBool_t result = NONE_BOOL;\n");
ast_t *comparison =
new (ast_t, .file = ast->file, .start = ast->start, .end = ast->end, .tag = op,
.__data.Plus.lhs = LiteralCode(Text("prev"), .type = item_value_type), .__data.Plus.rhs = item_value);
body->__data.InlineCCode.chunks = new (
ast_list_t, .ast = FakeAST(TextLiteral, Texts("if (result == NONE_BOOL) {\n"
" prev = ",
compile(body_scope, item_value),
";\n"
" result = yes;\n"
"} else {\n"
" if (",
compile(body_scope, comparison), ") {\n",
" prev = ", compile(body_scope, item_value), ";\n",
" } else {\n"
" result = no;\n",
" break;\n", " }\n", "}\n")));
code = Texts(code, compile_statement(env, loop), "\nresult;})");
return code;
} else if (op == Min || op == Max) {
// Min/max:
Text_t superlative = op == Min ? Text("min") : Text("max");
Text_t code = Texts("({ // Reduction:\n", compile_declaration(item_t, superlative),
";\n"
"Bool_t has_value = no;\n");
Text_t item_code = compile(body_scope, item);
ast_e cmp_op = op == Min ? LessThan : GreaterThan;
if (reduction->key) {
env_t *key_scope = fresh_scope(env);
set_binding(key_scope, "$", item_t, item_code);
type_t *key_type = get_type(key_scope, reduction->key);
Text_t superlative_key = op == Min ? Text("min_key") : Text("max_key");
code = Texts(code, compile_declaration(key_type, superlative_key), ";\n");
ast_t *comparison = new (ast_t, .file = ast->file, .start = ast->start, .end = ast->end, .tag = cmp_op,
.__data.Plus.lhs = LiteralCode(Text("key"), .type = key_type),
.__data.Plus.rhs = LiteralCode(superlative_key, .type = key_type));
body->__data.InlineCCode.chunks = new (
ast_list_t, .ast = FakeAST(TextLiteral, Texts(compile_declaration(key_type, Text("key")), " = ",
compile(key_scope, reduction->key), ";\n",
"if (!has_value || ", compile(body_scope, comparison),
") {\n"
" ",
superlative, " = ", compile(body_scope, item),
";\n"
" ",
superlative_key,
" = key;\n"
" has_value = yes;\n"
"}\n")));
} else {
ast_t *comparison =
new (ast_t, .file = ast->file, .start = ast->start, .end = ast->end, .tag = cmp_op,
.__data.Plus.lhs = item, .__data.Plus.rhs = LiteralCode(superlative, .type = item_t));
body->__data.InlineCCode.chunks = new (
ast_list_t, .ast = FakeAST(TextLiteral, Texts("if (!has_value || ", compile(body_scope, comparison),
") {\n"
" ",
superlative, " = ", compile(body_scope, item),
";\n"
" has_value = yes;\n"
"}\n")));
}
code = Texts(code, compile_statement(env, loop), "\nhas_value ? ", promote_to_optional(item_t, superlative),
" : ", compile_none(item_t), ";})");
return code;
} else {
// Accumulator-style reductions like +, ++, *, etc.
type_t *reduction_type = Match(get_type(env, ast), OptionalType)->type;
ast_t *item_value = item;
if (reduction->key) {
set_binding(body_scope, "$", item_t, compile(body_scope, item));
item_value = reduction->key;
}
Text_t code = Texts("({ // Reduction:\n", compile_declaration(reduction_type, Text("reduction")),
";\n"
"Bool_t has_value = no;\n");
// For the special case of (or)/(and), we need to early out if we
// can:
Text_t early_out = EMPTY_TEXT;
if (op == Compare) {
if (reduction_type->tag != IntType || Match(reduction_type, IntType)->bits != TYPE_IBITS32)
code_err(ast, "<> reductions are only supported for Int32 "
"values");
} else if (op == And) {
if (reduction_type->tag == BoolType) early_out = Text("if (!reduction) break;");
else if (reduction_type->tag == OptionalType)
early_out = Texts("if (", check_none(reduction_type, Text("reduction")), ") break;");
} else if (op == Or) {
if (reduction_type->tag == BoolType) early_out = Text("if (reduction) break;");
else if (reduction_type->tag == OptionalType)
early_out = Texts("if (!", check_none(reduction_type, Text("reduction")), ") break;");
}
ast_t *combination = new (ast_t, .file = ast->file, .start = ast->start, .end = ast->end, .tag = op,
.__data.Plus.lhs = LiteralCode(Text("reduction"), .type = reduction_type),
.__data.Plus.rhs = item_value);
body->__data.InlineCCode.chunks = new (
ast_list_t, .ast = FakeAST(TextLiteral, Texts("if (!has_value) {\n"
" reduction = ",
compile(body_scope, item_value),
";\n"
" has_value = yes;\n"
"} else {\n"
" reduction = ",
compile(body_scope, combination), ";\n", early_out, "}\n")));
code =
Texts(code, compile_statement(env, loop), "\nhas_value ? ",
promote_to_optional(reduction_type, Text("reduction")), " : ", compile_none(reduction_type), ";})");
return code;
}
}
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