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gen: fix evaluating the receiver of array methods (.map(), .filter(), etc) more than once (#7130)

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spaceface777 2020-12-04 19:29:34 +01:00 committed by GitHub
parent f21b2b41ac
commit 52fb7033c3
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2 changed files with 28 additions and 11 deletions

View File

@ -4767,16 +4767,14 @@ fn (mut g Gen) gen_array_map(node ast.CallExpr) {
if inp_sym.kind != .array {
verror('map() requires an array')
}
g.writeln('')
g.write('int ${tmp}_len = ')
g.write('${g.typ(node.left_type)} ${tmp}_orig = ')
g.expr(node.left)
g.writeln('.len;')
g.writeln(';')
g.write('int ${tmp}_len = ${tmp}_orig.len;')
g.writeln('$ret_typ $tmp = __new_array(0, ${tmp}_len, sizeof($ret_elem_type));')
i := g.new_tmp_var()
g.writeln('for (int $i = 0; $i < ${tmp}_len; ++$i) {')
g.write('\t$inp_elem_type it = (($inp_elem_type*) ')
g.expr(node.left)
g.writeln('.data)[$i];')
g.write('\t$inp_elem_type it = (($inp_elem_type*) ${tmp}_orig.data)[$i];')
g.write('\t$ret_elem_type ti = ')
expr := node.args[0].expr
match expr {
@ -4919,14 +4917,13 @@ fn (mut g Gen) gen_array_filter(node ast.CallExpr) {
info := sym.info as table.Array
styp := g.typ(node.return_type)
elem_type_str := g.typ(info.elem_type)
g.write('\nint ${tmp}_len = ')
g.write('${g.typ(node.left_type)} ${tmp}_orig = ')
g.expr(node.left)
g.writeln('.len;')
g.writeln(';')
g.write('int ${tmp}_len = ${tmp}_orig.len;')
g.writeln('$styp $tmp = __new_array(0, ${tmp}_len, sizeof($elem_type_str));')
g.writeln('for (int i = 0; i < ${tmp}_len; ++i) {')
g.write(' $elem_type_str it = (($elem_type_str*) ')
g.expr(node.left)
g.writeln('.data)[i];')
g.writeln(' $elem_type_str it = (($elem_type_str*) ${tmp}_orig.data)[i];')
g.write('if (')
expr := node.args[0].expr
match expr {

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@ -0,0 +1,20 @@
struct Counter {
mut:
val int
}
// if this is called more than once, the test'll fail
fn (mut c Counter) new_arr(msg string) []int {
if c.val > 0 { panic(msg) }
c.val++
return [1, 3, 2]
}
fn test_array_eval_count() {
// `new_arr()` should only be evaluated once, not on every iteration
mut a1 := Counter{}
assert a1.new_arr('map() failed').map(it * 2) == [2, 6, 4]
mut a2 := Counter{}
assert a2.new_arr('filter() failed').filter(it < 3) == [1, 2]
}