label.go

Documentation: cuelang.org/go/internal/core/compile

     1  // Copyright 2020 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 compile
    16  
    17  import (
    18  	"github.com/cockroachdb/apd/v3"
    19  	"golang.org/x/text/unicode/norm"
    20  
    21  	"cuelang.org/go/cue/ast"
    22  	"cuelang.org/go/cue/literal"
    23  	"cuelang.org/go/cue/token"
    24  	"cuelang.org/go/internal/core/adt"
    25  )
    26  
    27  // LabelFromNode converts an ADT node to a feature.
    28  func (c *compiler) label(n ast.Node) adt.Feature {
    29  	index := c.index
    30  	switch x := n.(type) {
    31  	case *ast.Ident:
    32  		if x.Name == "_" {
    33  			return adt.InvalidLabel
    34  		}
    35  		return adt.MakeIdentLabel(c.index, x.Name, c.pkgPath)
    36  
    37  	case *ast.BasicLit:
    38  		switch x.Kind {
    39  		case token.STRING:
    40  			const msg = "invalid string label: %v"
    41  			s, err := literal.Unquote(x.Value)
    42  			if err != nil {
    43  				c.errf(n, msg, err)
    44  				return adt.InvalidLabel
    45  			}
    46  
    47  			i := int64(index.StringToIndex(norm.NFC.String(s)))
    48  			f, err := adt.MakeLabel(n, i, adt.StringLabel)
    49  			if err != nil {
    50  				c.errf(n, msg, err)
    51  			}
    52  			return f
    53  
    54  		case token.INT:
    55  			const msg = "invalid int label: %v"
    56  			if err := literal.ParseNum(x.Value, &c.num); err != nil {
    57  				c.errf(n, msg, err)
    58  				return adt.InvalidLabel
    59  			}
    60  
    61  			var d apd.Decimal
    62  			if err := c.num.Decimal(&d); err != nil {
    63  				c.errf(n, msg, err)
    64  				return adt.InvalidLabel
    65  			}
    66  
    67  			i, err := d.Int64()
    68  			if err != nil {
    69  				c.errf(n, msg, err)
    70  				return adt.InvalidLabel
    71  			}
    72  
    73  			f, err := adt.MakeLabel(n, i, adt.IntLabel)
    74  			if err != nil {
    75  				c.errf(n, msg, err)
    76  				return adt.InvalidLabel
    77  			}
    78  			return f
    79  
    80  		case token.FLOAT:
    81  			_ = c.errf(n, "float %s cannot be used as label", x.Value)
    82  			return adt.InvalidLabel
    83  
    84  		default: // keywords (null, true, false, for, in, if, let)
    85  			i := index.StringToIndex(x.Kind.String())
    86  			f, err := adt.MakeLabel(n, i, adt.StringLabel)
    87  			if err != nil {
    88  				c.errf(n, "invalid string label: %v", err)
    89  			}
    90  			return f
    91  		}
    92  
    93  	default:
    94  		c.errf(n, "unsupported label node type %T", n)
    95  		return adt.InvalidLabel
    96  	}
    97  }
    98  
    99  // A labeler converts an AST node to a string representation.
   100  type labeler interface {
   101  	labelString() string
   102  }
   103  
   104  type fieldLabel ast.Field
   105  
   106  func (l *fieldLabel) labelString() string {
   107  	lab := l.Label
   108  
   109  	if a, ok := lab.(*ast.Alias); ok {
   110  		if x, _ := a.Expr.(ast.Label); x != nil {
   111  			lab = x
   112  		}
   113  	}
   114  
   115  	switch x := lab.(type) {
   116  	case *ast.Ident:
   117  		return x.Name
   118  
   119  	case *ast.BasicLit:
   120  		if x.Kind == token.STRING {
   121  			s, err := literal.Unquote(x.Value)
   122  			if err == nil && ast.IsValidIdent(s) {
   123  				return s
   124  			}
   125  		}
   126  		return x.Value
   127  
   128  	case *ast.ListLit:
   129  		return "[]" // TODO: more detail
   130  
   131  	case *ast.Interpolation:
   132  		return "?"
   133  		// case *ast.ParenExpr:
   134  	}
   135  	return "<unknown>"
   136  }
   137  
   138  type forScope ast.ForClause
   139  
   140  func (l *forScope) labelString() string {
   141  	// TODO: include more info in square brackets.
   142  	return "for[]"
   143  }
   144  
   145  type letScope ast.LetClause
   146  
   147  func (l *letScope) labelString() string {
   148  	// TODO: include more info in square brackets.
   149  	return "let[]"
   150  }
   151
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