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checker: smartcast in for loops (#7942)

pull/7952/head
Daniel Däschle 2021-01-07 21:35:32 +01:00 committed by GitHub
parent 5dbc19410c
commit 88d18f3303
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5 changed files with 174 additions and 123 deletions
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1
CHANGELOG.md
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@ -5,6 +5,7 @@
- Overloading of `>`, `<`, `!=`, and `==` operators.
- New struct updating syntax: `User{ ...u, name: 'new' }` to replace `{ u | name: 'new' }`.
- `byte.str()` has been fixed and works like with all other numbers. `byte.ascii_str()` has been added.
- Smart cast in for-loops: `for mut x is string {}`
## V 0.2.1
*30 Dec 2020*

1
vlib/v/ast/ast.v
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@ -120,6 +120,7 @@ pub mut:
pub fn (e &SelectorExpr) root_ident() Ident {
mut root := e.expr
for root is SelectorExpr {
// TODO: remove this line
selector_expr := root as SelectorExpr
root = selector_expr.expr
}

239
vlib/v/checker/checker.v
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@ -2886,19 +2886,7 @@ fn (mut c Checker) stmt(node ast.Stmt) {
c.in_for_count--
}
ast.ForStmt {
c.in_for_count++
prev_loop_label := c.loop_label
c.expected_type = table.bool_type
typ := c.expr(node.cond)
if !node.is_inf && typ.idx() != table.bool_type_idx && !c.pref.translated {
c.error('non-bool used as for condition', node.pos)
}
// TODO: update loop var type
// how does this work currenly?
c.check_loop_label(node.label, node.pos)
c.stmts(node.stmts)
c.loop_label = prev_loop_label
c.in_for_count--
c.for_stmt(mut node)
}
ast.GlobalDecl {
for field in node.fields {
@ -3884,60 +3872,7 @@ fn (mut c Checker) match_exprs(mut node ast.MatchExpr, cond_type_sym table.TypeS
} else {
expr_type = expr_types[0].typ
}
match mut node.cond {
ast.SelectorExpr {
mut is_mut := false
mut sum_type_casts := []table.Type{}
expr_sym := c.table.get_type_symbol(node.cond.expr_type)
if field := c.table.struct_find_field(expr_sym, node.cond.field_name) {
if field.is_mut {
root_ident := node.cond.root_ident()
if v := branch.scope.find_var(root_ident.name) {
is_mut = v.is_mut
}
}
}
if field := branch.scope.find_struct_field(node.cond.expr_type,
node.cond.field_name) {
sum_type_casts << field.sum_type_casts
}
// smartcast either if the value is immutable or if the mut argument is explicitly given
if !is_mut || node.cond.is_mut {
sum_type_casts << expr_type
branch.scope.register_struct_field(ast.ScopeStructField{
struct_type: node.cond.expr_type
name: node.cond.field_name
typ: node.cond_type
sum_type_casts: sum_type_casts
pos: node.cond.pos
})
}
}
ast.Ident {
mut is_mut := false
mut sum_type_casts := []table.Type{}
mut is_already_casted := false
if node.cond.obj is ast.Var {
v := node.cond.obj as ast.Var
is_mut = v.is_mut
sum_type_casts << v.sum_type_casts
is_already_casted = v.pos.pos == node.cond.pos.pos
}
// smartcast either if the value is immutable or if the mut argument is explicitly given
if (!is_mut || node.cond.is_mut) && !is_already_casted {
sum_type_casts << expr_type
branch.scope.register(ast.Var{
name: node.cond.name
typ: node.cond_type
pos: node.cond.pos
is_used: true
is_mut: node.cond.is_mut
sum_type_casts: sum_type_casts
})
}
}
else {}
}
c.smartcast_sumtype(node.cond, node.cond_type, expr_type, mut branch.scope)
}
}
}
@ -4017,6 +3952,63 @@ fn (mut c Checker) match_exprs(mut node ast.MatchExpr, cond_type_sym table.TypeS
c.error(err_details, node.pos)
}
// smartcast takes the expression with the current type which should be smartcasted to the target type in the given scope
fn (c Checker) smartcast_sumtype(expr ast.Expr, cur_type table.Type, to_type table.Type, mut scope ast.Scope) {
match mut expr {
ast.SelectorExpr {
mut is_mut := false
mut sum_type_casts := []table.Type{}
expr_sym := c.table.get_type_symbol(expr.expr_type)
if field := c.table.struct_find_field(expr_sym, expr.field_name) {
if field.is_mut {
root_ident := expr.root_ident()
if v := scope.find_var(root_ident.name) {
is_mut = v.is_mut
}
}
}
if field := scope.find_struct_field(expr.expr_type, expr.field_name) {
sum_type_casts << field.sum_type_casts
}
// smartcast either if the value is immutable or if the mut argument is explicitly given
if !is_mut || expr.is_mut {
sum_type_casts << to_type
scope.register_struct_field(ast.ScopeStructField{
struct_type: expr.expr_type
name: expr.field_name
typ: cur_type
sum_type_casts: sum_type_casts
pos: expr.pos
})
}
}
ast.Ident {
mut is_mut := false
mut sum_type_casts := []table.Type{}
mut is_already_casted := false
if expr.obj is ast.Var {
v := expr.obj as ast.Var
is_mut = v.is_mut
sum_type_casts << v.sum_type_casts
is_already_casted = v.pos.pos == expr.pos.pos
}
// smartcast either if the value is immutable or if the mut argument is explicitly given
if (!is_mut || expr.is_mut) && !is_already_casted {
sum_type_casts << to_type
scope.register(ast.Var{
name: expr.name
typ: cur_type
pos: expr.pos
is_used: true
is_mut: expr.is_mut
sum_type_casts: sum_type_casts
})
}
}
else {}
}
}
pub fn (mut c Checker) select_expr(mut node ast.SelectExpr) table.Type {
node.is_expr = c.expected_type != table.void_type
node.expected_type = c.expected_type
@ -4114,6 +4106,45 @@ pub fn (mut c Checker) unsafe_expr(mut node ast.UnsafeExpr) table.Type {
return t
}
fn (mut c Checker) for_stmt(mut node ast.ForStmt) {
c.in_for_count++
prev_loop_label := c.loop_label
c.expected_type = table.bool_type
typ := c.expr(node.cond)
if !node.is_inf && typ.idx() != table.bool_type_idx && !c.pref.translated {
c.error('non-bool used as for condition', node.pos)
}
if node.cond is ast.InfixExpr {
infix := node.cond
if infix.op == .key_is {
if (infix.left is ast.Ident ||
infix.left is ast.SelectorExpr) &&
infix.right is ast.Type {
right_expr := infix.right as ast.Type
is_variable := if mut infix.left is ast.Ident {
infix.left.kind == .variable
} else {
true
}
left_type := c.expr(infix.left)
left_sym := c.table.get_type_symbol(left_type)
if is_variable {
if left_sym.kind == .sum_type {
c.smartcast_sumtype(infix.left, infix.left_type, right_expr.typ, mut
node.scope)
}
}
}
}
}
// TODO: update loop var type
// how does this work currenly?
c.check_loop_label(node.label, node.pos)
c.stmts(node.stmts)
c.loop_label = prev_loop_label
c.in_for_count--
}
pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
if_kind := if node.is_comptime { '\$if' } else { 'if' }
expr_required := c.expected_type != table.void_type
@ -4167,68 +4198,30 @@ pub fn (mut c Checker) if_expr(mut node ast.IfExpr) table.Type {
} else {
true
}
// Register shadow variable or `as` variable with actual type
if is_variable {
// TODO: merge this code with match_expr because it has the same logic implemented
if left_sym.kind in [.interface_, .sum_type] {
mut is_mut := false
if mut infix.left is ast.Ident {
if infix.left is ast.Ident && left_sym.kind == .interface_ {
// TODO: rewrite interface smartcast
left := infix.left as ast.Ident
mut is_mut := false
mut sum_type_casts := []table.Type{}
if v := branch.scope.find_var(infix.left.name) {
if v := branch.scope.find_var(left.name) {
is_mut = v.is_mut
sum_type_casts << v.sum_type_casts
}
if left_sym.kind == .sum_type {
// smartcast either if the value is immutable or if the mut argument is explicitly given
if !is_mut || infix.left.is_mut {
sum_type_casts << right_expr.typ
branch.scope.register(ast.Var{
name: infix.left.name
typ: infix.left_type
sum_type_casts: sum_type_casts
pos: infix.left.pos
is_used: true
is_mut: is_mut
})
}
} else if left_sym.kind == .interface_ {
branch.scope.register(ast.Var{
name: infix.left.name
typ: right_expr.typ.to_ptr()
sum_type_casts: sum_type_casts
pos: infix.left.pos
is_used: true
is_mut: is_mut
})
// TODO: remove that later @danieldaeschle
node.branches[i].smartcast = true
}
} else if mut infix.left is ast.SelectorExpr {
mut sum_type_casts := []table.Type{}
expr_sym := c.table.get_type_symbol(infix.left.expr_type)
if field := c.table.struct_find_field(expr_sym, infix.left.field_name) {
if field.is_mut {
root_ident := infix.left.root_ident()
if root_ident.obj is ast.Var {
is_mut = root_ident.obj.is_mut
}
}
}
if field := branch.scope.find_struct_field(infix.left.expr_type,
infix.left.field_name) {
sum_type_casts << field.sum_type_casts
}
// smartcast either if the value is immutable or if the mut argument is explicitly given
if (!is_mut || infix.left.is_mut) && left_sym.kind == .sum_type {
sum_type_casts << right_expr.typ
branch.scope.register_struct_field(ast.ScopeStructField{
struct_type: infix.left.expr_type
name: infix.left.field_name
typ: infix.left_type
sum_type_casts: sum_type_casts
pos: infix.left.pos
})
}
branch.scope.register(ast.Var{
name: left.name
typ: right_expr.typ.to_ptr()
sum_type_casts: sum_type_casts
pos: left.pos
is_used: true
is_mut: is_mut
})
// TODO: needs to be removed
node.branches[i].smartcast = true
} else {
c.smartcast_sumtype(infix.left, infix.left_type, right_expr.typ, mut
branch.scope)
}
}
}

3
vlib/v/parser/for.v
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@ -177,6 +177,8 @@ fn (mut p Parser) for_stmt() ast.Stmt {
// `for cond {`
cond := p.expr(0)
p.inside_for = false
// extra scope for the body
p.open_scope()
stmts := p.parse_block_no_scope(false)
pos.last_line = p.prev_tok.line_nr - 1
for_stmt := ast.ForStmt{
@ -186,5 +188,6 @@ fn (mut p Parser) for_stmt() ast.Stmt {
scope: p.scope
}
p.close_scope()
p.close_scope()
return for_stmt
}

53
vlib/v/tests/for_smartcast_test.v 100644
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@ -0,0 +1,53 @@
type Node = Expr | string
type Expr = IfExpr | IntegerLiteral
struct IntegerLiteral {}
struct IfExpr {
pos int
}
struct NodeWrapper {
node Node
}
fn test_nested_sumtype_selector() {
c := NodeWrapper{Node(Expr(IfExpr{pos: 1}))}
for c.node is Expr {
assert typeof(c.node).name == 'Expr'
break
}
}
struct Milk {
mut:
name string
}
struct Eggs {
mut:
name string
}
type Food = Milk | Eggs
struct FoodWrapper {
mut:
food Food
}
fn test_match_mut() {
mut f := Food(Eggs{'test'})
for mut f is Eggs {
f.name = 'eggs'
assert f.name == 'eggs'
break
}
}
fn test_conditional_break() {
mut f := Food(Eggs{'test'})
for mut f is Eggs {
f = Milk{'test'}
}
assert true
}