simplify.go

Documentation: cuelang.org/go/tools/fix

     1  // Copyright 2021 CUE Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package fix
    16  
    17  import (
    18  	"cuelang.org/go/cue/ast"
    19  	"cuelang.org/go/cue/ast/astutil"
    20  	"cuelang.org/go/cue/token"
    21  )
    22  
    23  func simplify(f *ast.File) *ast.File {
    24  	// Rewrite disjunctions with _ to _.
    25  	f = astutil.Apply(f, nil, func(c astutil.Cursor) bool {
    26  		if x, ok := c.Node().(ast.Expr); ok {
    27  			if y := elideTop(x); x != y {
    28  				c.Replace(y)
    29  			}
    30  		}
    31  		return true
    32  	}).(*ast.File)
    33  
    34  	return f
    35  }
    36  
    37  func elideTop(x ast.Expr) ast.Expr {
    38  	switch x := x.(type) {
    39  	case *ast.BinaryExpr:
    40  		switch x.Op {
    41  		case token.OR:
    42  			if isTop(x.X) {
    43  				return x.X
    44  			}
    45  			if isTop(x.Y) {
    46  				ast.SetRelPos(x.Y, token.NoRelPos)
    47  				return x.Y
    48  			}
    49  
    50  		case token.AND:
    51  			if isTop(x.X) {
    52  				ast.SetRelPos(x.Y, token.NoRelPos)
    53  				return x.Y
    54  			}
    55  			if isTop(x.Y) {
    56  				return x.X
    57  			}
    58  		}
    59  
    60  	case *ast.ParenExpr:
    61  		switch x.X.(type) {
    62  		case *ast.BinaryExpr, *ast.UnaryExpr:
    63  		default:
    64  			return x.X
    65  		}
    66  	}
    67  	return x
    68  }
    69  
    70  func isTop(x ast.Expr) bool {
    71  	v, ok := x.(*ast.Ident)
    72  	return ok && v.Name == "_"
    73  }
    74
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