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cue/ast,cue/ast/astutil: add Predeclared sentinel for builtin references
Add ast.Predeclared, a sentinel node that can be used as ast.Ident.Node
to mark a reference to a predeclared identifier like "self" or "int".
When Sanitize encounters a shadowed identifier with this sentinel, it
renames it to the "__"-prefixed form (e.g. "__self") which cannot be
shadowed, rather than introducing a let alias.
For #4151.
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: Iccc6cd07da85898230891bd135f7dc964fe460af
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1231144
Reviewed-by: Marcel van Lohuizen <mpvl@gmail.com>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
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-2
+16
cue/ast/ast.go
+16
cue/ast/ast.go
···
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expr
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}
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// Predeclared is a sentinel [Node] that can be used as [Ident.Node]
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// for an identifier referring to a predeclared name such as "self" or "int".
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//
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// When [cuelang.org/go/cue/ast/astutil.Sanitize] encounters an identifier
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// whose Node is this sentinel and the name is shadowed in scope, it renames
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// the identifier to its "__"-prefixed form (e.g. "__self") to avoid the shadow.
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var Predeclared Node = &predeclaredNode{}
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type predeclaredNode struct {
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comments
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}
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func (n *predeclaredNode) Pos() token.Pos { return token.NoPos }
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func (n *predeclaredNode) pos() *token.Pos { return nil }
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func (n *predeclaredNode) End() token.Pos { return token.NoPos }
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// A BasicLit node represents a literal of basic type.
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type BasicLit struct {
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ValuePos token.Pos // literal position
+9
-2
cue/ast/astutil/sanitize.go
+9
-2
cue/ast/astutil/sanitize.go
···
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// - handle comprehensions
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// - change field from foo to "foo" if it isn't referenced, rather than
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// relying on introducing a unique alias.
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-
// - change a predeclared identifier reference to use the __ident form,
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// instead of introducing an alias.
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// Sanitize rewrites File f in place to be well-formed after automated
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// construction of an AST.
···
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if node.node == n.Node {
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return true
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}
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// A predeclared reference (e.g. "self") is shadowed by a local
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// declaration. Use the "__"-prefixed form to avoid the shadow.
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if n.Node == ast.Predeclared {
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n.Name = "__" + n.Name
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n.Node = nil
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n.Scope = nil
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return false
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}
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// n.Node != node and are both not nil and n.Node is not an ImportSpec.