all: if-is smartcast part 1 (#5730)

pull/5756/head
Daniel Däschle 2020-07-08 15:17:28 +02:00 committed by GitHub
parent 3b0dfd9ae1
commit b62bf59c21
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6 changed files with 58 additions and 14 deletions

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@ -425,10 +425,10 @@ pub mut:
pub struct IfExpr {
pub:
tok_kind token.Kind
branches []IfBranch
left Expr // `a` in `a := if ...`
pos token.Position
pub mut:
branches []IfBranch
is_expr bool
typ table.Type
has_else bool
@ -439,7 +439,10 @@ pub:
cond Expr
stmts []Stmt
pos token.Position
body_pos token.Position
comments []Comment
pub mut:
smartcast bool // should only be true if cond is `x is sumtype`, it will be set in checker - if_expr
}
pub struct LockExpr {

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@ -286,7 +286,7 @@ pub fn (node Stmt) str() string {
}
}
out += left.str()
if i < it.left.len - 1 {
if i < node.left.len - 1 {
out += ','
}
}

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@ -2623,6 +2623,29 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
c.error('non-bool type `$typ_sym.name` used as if condition', branch.pos)
}
}
// smartcast sumtypes when using `is`
if branch.cond is ast.InfixExpr {
infix := branch.cond as ast.InfixExpr
if infix.op == .key_is && infix.left is ast.Ident && infix.right is ast.Type {
left_expr := infix.left as ast.Ident
right_expr := infix.right as ast.Type
if left_expr.kind == .variable {
// Register shadow variable or `as` variable with actual type
left_sym := c.table.get_type_symbol(infix.left_type)
if left_sym.kind == .sum_type {
mut scope := c.file.scope.innermost(branch.body_pos.pos)
scope.register('it', ast.Var{
name: 'it'
typ: right_expr.typ.to_ptr()
pos: left_expr.pos
is_used: true
is_mut: left_expr.is_mut
})
node.branches[i].smartcast = true
}
}
}
}
c.stmts(branch.stmts)
if expr_required {
if branch.stmts.len > 0 && branch.stmts[branch.stmts.len - 1] is ast.ExprStmt {

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@ -2311,6 +2311,20 @@ fn (mut g Gen) if_expr(node ast.IfExpr) {
} else if i == node.branches.len - 1 && node.has_else {
g.writeln('} else {')
}
if branch.smartcast && branch.stmts.len > 0 {
infix := branch.cond as ast.InfixExpr
right_type := infix.right as ast.Type
left_type := infix.left_type
it_type := g.typ(right_type.typ)
g.write('\t$it_type* it = ($it_type*)')
g.expr(infix.left)
if left_type.is_ptr() {
g.write('->')
} else {
g.write('.')
}
g.writeln('obj;')
}
g.stmts(branch.stmts)
}
if is_guard {

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@ -663,27 +663,27 @@ fn (mut g JsGen) gen_assert_stmt(a ast.AssertStmt) {
g.writeln('}')
}
fn (mut g JsGen) gen_assign_stmt(it ast.AssignStmt) {
if it.left.len > it.right.len {
fn (mut g JsGen) gen_assign_stmt(stmt ast.AssignStmt) {
if stmt.left.len > stmt.right.len {
// multi return
g.write('const [')
for i, left in it.left {
for i, left in stmt.left {
if !left.is_blank_ident() {
g.expr(left)
}
if i < it.left.len - 1 {
if i < stmt.left.len - 1 {
g.write(', ')
}
}
g.write('] = ')
g.expr(it.right[0])
g.expr(stmt.right[0])
g.writeln(';')
} else {
// `a := 1` | `a,b := 1,2`
for i, left in it.left {
mut op := it.op
if it.op == .decl_assign { op = .assign }
val := it.right[i]
for i, left in stmt.left {
mut op := stmt.op
if stmt.op == .decl_assign { op = .assign }
val := stmt.right[i]
mut is_mut := false
if left is ast.Ident {
ident := left as ast.Ident
@ -698,13 +698,13 @@ fn (mut g JsGen) gen_assign_stmt(it ast.AssignStmt) {
}
}
mut styp := g.typ(it.left_types[i])
mut styp := g.typ(stmt.left_types[i])
if !g.inside_loop && styp.len > 0 {
g.doc.gen_typ(styp)
}
if it.op == .decl_assign {
if stmt.op == .decl_assign {
if g.inside_loop || is_mut {
g.write('let ')
} else {

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@ -31,9 +31,11 @@ fn (mut p Parser) if_expr() ast.IfExpr {
has_else = true
p.inside_if = false
end_pos := p.prev_tok.position()
body_pos := p.tok.position()
branches << ast.IfBranch{
stmts: p.parse_block()
pos: start_pos.extend(end_pos)
body_pos: body_pos.extend(p.tok.position())
comments: comments
}
comments = []
@ -63,7 +65,8 @@ fn (mut p Parser) if_expr() ast.IfExpr {
cond = p.expr(0)
}
end_pos := p.prev_tok.position()
p.inside_if = false
body_pos := p.tok.position()
p.inside_if = false
stmts := p.parse_block()
if is_or {
p.close_scope()
@ -72,6 +75,7 @@ fn (mut p Parser) if_expr() ast.IfExpr {
cond: cond
stmts: stmts
pos: start_pos.extend(end_pos)
body_pos: body_pos.extend(p.tok.position())
comments: comments
}
comments = []