github.com/joomcode/cue@v0.4.4-0.20221111115225-539fe3512047/pkg/struct/struct.go (about)

     1  // Copyright 2019 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 struct defines utilities for struct types.
    16  package structs
    17  
    18  import (
    19  	"github.com/joomcode/cue/cue"
    20  	"github.com/joomcode/cue/cue/errors"
    21  	"github.com/joomcode/cue/cue/token"
    22  	"github.com/joomcode/cue/internal/core/adt"
    23  )
    24  
    25  // MinFields validates the minimum number of fields that are part of a struct.
    26  // It can only be used as a validator, for instance `MinFields(3)`.
    27  //
    28  // Only fields that are part of the data model count. This excludes hidden
    29  // fields, optional fields, and definitions.
    30  func MinFields(object *cue.Struct, n int) *adt.Bottom {
    31  	iter := object.Fields(cue.Hidden(false), cue.Optional(false))
    32  	count := 0
    33  	for iter.Next() {
    34  		count++
    35  	}
    36  	if count < n {
    37  		return &adt.Bottom{
    38  			Code: adt.IncompleteError, // could still be resolved
    39  			Err:  errors.Newf(token.NoPos, "len(fields) < MinFields(%[2]d) (%[1]d < %[2]d)", count, n),
    40  		}
    41  	}
    42  	return nil
    43  }
    44  
    45  // MaxFields validates the maximum number of fields that are part of a struct.
    46  // It can only be used as a validator, for instance `MaxFields(3)`.
    47  //
    48  // Only fields that are part of the data model count. This excludes hidden
    49  // fields, optional fields, and definitions.
    50  func MaxFields(object *cue.Struct, n int) (bool, error) {
    51  	iter := object.Fields(cue.Hidden(false), cue.Optional(false))
    52  	count := 0
    53  	for iter.Next() {
    54  		count++
    55  	}
    56  	// permanent error is okay here.
    57  	return count <= n, nil
    58  }