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// Package buildattr implements support for interpreting the @if
// build attributes in CUE files.
package buildattr
import (
"cuelang.org/go/cue/ast"
"cuelang.org/go/cue/errors"
"cuelang.org/go/cue/parser"
"cuelang.org/go/cue/token"
)
// ShouldIgnoreFile reports whether a File contains an @ignore() file-level
// attribute and hence should be ignored.
func ShouldIgnoreFile(f *ast.File) bool {
ignore, _, _ := getBuildAttr(f)
return ignore
}
// ShouldBuildFile reports whether a File should be included based on its
// attributes. It uses tagIsSet to determine whether a given attribute
// key should be treated as set.
//
// It also returns the build attribute if one was found.
func ShouldBuildFile(f *ast.File, tagIsSet func(key string) bool) (bool, *ast.Attribute, errors.Error) {
ignore, a, err := getBuildAttr(f)
if ignore || err != nil {
return false, a, err
}
if a == nil {
return true, nil, nil
}
_, body := a.Split()
expr, parseErr := parser.ParseExpr("", body)
if parseErr != nil {
return false, a, errors.Promote(parseErr, "")
}
include, err := shouldInclude(expr, tagIsSet)
if err != nil {
return false, a, err
}
return include, a, nil
}
func getBuildAttr(f *ast.File) (ignore bool, a *ast.Attribute, err errors.Error) {
for _, d := range f.Decls {
switch x := d.(type) {
case *ast.Attribute:
switch key, _ := x.Split(); key {
case "ignore":
return true, x, nil
case "if":
if a != nil {
err := errors.Newf(d.Pos(), "multiple @if attributes")
err = errors.Append(err,
errors.Newf(a.Pos(), "previous declaration here"))
return false, a, err
}
a = x
}
case *ast.Package:
return false, a, nil
case *ast.CommentGroup:
default:
// If it's anything else, then we know we won't see a package
// clause so avoid scanning more than we need to (this
// could be a large file with no package clause)
return false, a, nil
}
}
return false, a, nil
}
func shouldInclude(expr ast.Expr, tagIsSet func(key string) bool) (bool, errors.Error) {
switch x := expr.(type) {
case *ast.Ident:
return tagIsSet(x.Name), nil
case *ast.ParenExpr:
return shouldInclude(x.X, tagIsSet)
case *ast.BinaryExpr:
switch x.Op {
case token.LAND, token.LOR:
a, err := shouldInclude(x.X, tagIsSet)
if err != nil {
return false, err
}
b, err := shouldInclude(x.Y, tagIsSet)
if err != nil {
return false, err
}
if x.Op == token.LAND {
return a && b, nil
}
return a || b, nil
default:
return false, errors.Newf(token.NoPos, "invalid operator %v in build attribute", x.Op)
}
case *ast.UnaryExpr:
if x.Op != token.NOT {
return false, errors.Newf(token.NoPos, "invalid operator %v in build attribute", x.Op)
}
v, err := shouldInclude(x.X, tagIsSet)
if err != nil {
return false, err
}
return !v, nil
default:
return false, errors.Newf(token.NoPos, "invalid type %T in build attribute", expr)
}
}
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