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// Copyright 2019 CUE Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package fix contains functionality for writing CUE files with legacy
// syntax to newer ones.
//
// Note: the transformations that are supported in this package will change
// over time.
package fix
import (
"cuelang.org/go/cue/ast"
"cuelang.org/go/cue/ast/astutil"
"cuelang.org/go/cue/token"
)
type Option func(*options)
type options struct {
simplify bool
}
// Simplify enables fixes that simplify the code, but are not strictly
// necessary.
func Simplify() Option {
return func(o *options) { o.simplify = true }
}
// File applies fixes to f and returns it. It alters the original f.
func File(f *ast.File, o ...Option) *ast.File {
var options options
for _, f := range o {
f(&options)
}
// Make sure we use the "after" function, and not the "before",
// because "before" will stop recursion early which creates
// problems with nested expressions.
f = astutil.Apply(f, nil, func(c astutil.Cursor) bool {
n := c.Node()
switch n := n.(type) {
case *ast.BinaryExpr:
switch n.Op {
case token.IDIV, token.IMOD, token.IQUO, token.IREM:
// Rewrite integer division operations to use builtins.
ast.SetRelPos(n.X, token.NoSpace)
c.Replace(&ast.CallExpr{
// Use the __foo version to prevent accidental shadowing.
Fun: ast.NewIdent("__" + n.Op.String()),
Args: []ast.Expr{n.X, n.Y},
})
case token.ADD, token.MUL:
// The fix here only works when at least one argument is a
// literal list. It would be better to be able to use CUE
// to infer type information, and then apply the fix to
// all places where we infer a list argument.
x, y := n.X, n.Y
_, xIsList := x.(*ast.ListLit)
_, yIsList := y.(*ast.ListLit)
_, xIsConcat := concatCallArgs(x)
_, yIsConcat := concatCallArgs(y)
if n.Op == token.ADD {
if !(xIsList || xIsConcat || yIsList || yIsConcat) {
break
}
// Rewrite list addition to use list.Concat
exprs := expandConcats(x, y)
ast.SetRelPos(x, token.NoSpace)
c.Replace(ast.NewCall(
ast.NewSel(&ast.Ident{
Name: "list",
Node: ast.NewImport(nil, "list"),
}, "Concat"), ast.NewList(exprs...)),
)
} else {
if !(xIsList || yIsList) {
break
}
// Rewrite list multiplication to use list.Repeat
if !xIsList {
x, y = y, x
}
ast.SetRelPos(x, token.NoSpace)
c.Replace(ast.NewCall(
ast.NewSel(&ast.Ident{
Name: "list",
Node: ast.NewImport(nil, "list"),
}, "Repeat"), x, y),
)
}
}
}
return true
}).(*ast.File)
if options.simplify {
f = simplify(f)
}
err := astutil.Sanitize(f)
// TODO: this File method is public, and its signature was fixed
// before we started calling Sanitize. Ideally, we want to return
// this error, but that would require deprecating this File method,
// and creating a new one, which might happen in due course if we
// also discover that we need to be a bit more flexible than just
// accepting a File.
if err != nil {
panic(err)
}
return f
}
func expandConcats(exprs ...ast.Expr) (result []ast.Expr) {
for _, expr := range exprs {
list, ok := concatCallArgs(expr)
if ok {
result = append(result, expandConcats(list.Elts...)...)
} else {
result = append(result, expr)
}
}
return result
}
func concatCallArgs(expr ast.Expr) (*ast.ListLit, bool) {
call, ok := expr.(*ast.CallExpr)
if !ok {
return nil, false
}
sel, ok := call.Fun.(*ast.SelectorExpr)
if !ok {
return nil, false
}
name, ok := sel.X.(*ast.Ident)
if !ok || name.Name != "list" {
return nil, false
}
name, ok = sel.Sel.(*ast.Ident)
if !ok || name.Name != "Concat" {
return nil, false
}
if len(call.Args) != 1 {
return nil, false
}
list, ok := call.Args[0].(*ast.ListLit)
if !ok {
return nil, false
}
return list, true
}
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