github.com/fabianvf/ocp-release-operator-sdk@v0.0.0-20190426141702-57620ee2f090/internal/util/yamlutil/scan.go (about)

     1  // Copyright 2018 The Operator-SDK 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 yamlutil
    16  
    17  import (
    18  	"bufio"
    19  	"bytes"
    20  	"io"
    21  
    22  	k8syaml "k8s.io/apimachinery/pkg/util/yaml"
    23  )
    24  
    25  const maxExecutiveEmpties = 100
    26  
    27  // Scanner scans a yaml manifest file for manifest tokens delimited by "---".
    28  // See bufio.Scanner for semantics.
    29  type Scanner struct {
    30  	reader  *k8syaml.YAMLReader
    31  	token   []byte // Last token returned by split.
    32  	err     error  // Sticky error.
    33  	empties int    // Count of successive empty tokens.
    34  	done    bool   // Scan has finished.
    35  }
    36  
    37  func NewYAMLScanner(b []byte) *Scanner {
    38  	r := bufio.NewReader(bytes.NewBuffer(b))
    39  	return &Scanner{reader: k8syaml.NewYAMLReader(r)}
    40  }
    41  
    42  func (s *Scanner) Err() error {
    43  	if s.err == io.EOF {
    44  		return nil
    45  	}
    46  	return s.err
    47  }
    48  
    49  func (s *Scanner) Scan() bool {
    50  	if s.done {
    51  		return false
    52  	}
    53  
    54  	var (
    55  		tok []byte
    56  		err error
    57  	)
    58  
    59  	for {
    60  		tok, err = s.reader.Read()
    61  		if err != nil {
    62  			if err == io.EOF {
    63  				s.done = true
    64  			}
    65  			s.err = err
    66  			return false
    67  		}
    68  		if len(bytes.TrimSpace(tok)) == 0 {
    69  			s.empties++
    70  			if s.empties > maxExecutiveEmpties {
    71  				panic("yaml.Scan: too many empty tokens without progressing")
    72  			}
    73  			continue
    74  		}
    75  		s.empties = 0
    76  		s.token = tok
    77  		return true
    78  	}
    79  }
    80  
    81  func (s *Scanner) Text() string {
    82  	return string(s.token)
    83  }
    84  
    85  func (s *Scanner) Bytes() []byte {
    86  	return s.token
    87  }