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cgen: new experimental simple if expression implementation

pull/6640/head
Alexander Medvednikov 2020-10-18 15:55:04 +02:00
parent 941f138934
commit 8a68714095
1 changed files with 33 additions and 3 deletions
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36
vlib/v/gen/cgen.v
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@ -71,6 +71,7 @@ mut:
inside_ternary int // ?: comma separated statements on a single line
inside_map_postfix bool // inside map++/-- postfix expr
inside_map_infix bool // inside map<</+=/-= infix expr
// inside_if_expr bool
ternary_names map[string]string
ternary_level_names map[string][]string
stmt_path_pos []int
@ -713,11 +714,18 @@ fn (mut g Gen) decrement_inside_ternary() {
}
fn (mut g Gen) stmts(stmts []ast.Stmt) {
g.stmts_with_tmp_var(stmts, '')
}
fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) {
g.indent++
if g.inside_ternary > 0 {
g.write('(')
}
for i, stmt in stmts {
if i == stmts.len - 1 && tmp_var != '' {
g.write('$tmp_var = ')
}
g.stmt(stmt)
if g.inside_ternary > 0 && i < stmts.len - 1 {
g.write(',')
@ -1992,7 +2000,7 @@ fn (mut g Gen) expr(node ast.Expr) {
// if g.fileis('1.strings') {
// println('before:' + node.autofree_pregen)
// }
if g.pref.autofree && !g.is_builtin_mod && g.strs_to_free0.len == 0 {
if g.pref.autofree && !g.is_builtin_mod && g.strs_to_free0.len == 0 { // && g.inside_ternary ==
// if len != 0, that means we are handling call expr inside call expr (arg)
// and it'll get messed up here, since it's handled recursively in autofree_call_pregen()
// so just skip it
@ -3137,7 +3145,22 @@ fn (mut g Gen) if_expr(node ast.IfExpr) {
g.comp_if(node)
return
}
if node.is_expr || g.inside_ternary != 0 {
// For simpe if expressions we can use C's `?:`
// `if x > 0 { 1 } else { 2 }` => `(x > 0) ? (1) : (2)`
// For if expressions with multiple statements or another if expression inside, it's much
// easier to use a temp var, than do C tricks with commas, introduce special vars etc
// (as it used to be done).
needs_tmp_var := node.is_expr && g.pref.experimental &&
(node.branches[0].stmts.len > 1 || node.branches[0].stmts[0] is ast.IfExpr)
tmp := if needs_tmp_var { g.new_tmp_var() } else { '' }
mut cur_line := ''
if needs_tmp_var {
g.write('/*experimental if expr*/')
styp := g.typ(node.typ)
// g.insert_before_stmt('$styp $tmp;')
cur_line = g.go_before_stmt(0)
g.writeln('$styp $tmp;')
} else if node.is_expr || g.inside_ternary != 0 {
g.inside_ternary++
g.write('(')
for i, branch in node.branches {
@ -3220,12 +3243,19 @@ fn (mut g Gen) if_expr(node ast.IfExpr) {
g.writeln('_object;')
g.writeln('\t$it_type* $branch.left_as_name = _sc_tmp_$branch.pos.pos;')
}
g.stmts(branch.stmts)
if needs_tmp_var {
g.stmts_with_tmp_var(branch.stmts, tmp)
} else {
g.stmts(branch.stmts)
}
}
if is_guard {
g.write('}')
}
g.writeln('}')
if needs_tmp_var {
g.writeln('$cur_line $tmp;')
}
}
fn (mut g Gen) index_expr(node ast.IndexExpr) {