github.com/evanw/esbuild@v0.21.4/internal/helpers/joiner.go (about)

     1  package helpers
     2  
     3  import (
     4  	"bytes"
     5  	"strings"
     6  )
     7  
     8  // This provides an efficient way to join lots of big string and byte slices
     9  // together. It avoids the cost of repeatedly reallocating as the buffer grows
    10  // by measuring exactly how big the buffer should be and then allocating once.
    11  // This is a measurable speedup.
    12  type Joiner struct {
    13  	strings  []joinerString
    14  	bytes    []joinerBytes
    15  	length   uint32
    16  	lastByte byte
    17  }
    18  
    19  type joinerString struct {
    20  	data   string
    21  	offset uint32
    22  }
    23  
    24  type joinerBytes struct {
    25  	data   []byte
    26  	offset uint32
    27  }
    28  
    29  func (j *Joiner) AddString(data string) {
    30  	if len(data) > 0 {
    31  		j.lastByte = data[len(data)-1]
    32  	}
    33  	j.strings = append(j.strings, joinerString{data, j.length})
    34  	j.length += uint32(len(data))
    35  }
    36  
    37  func (j *Joiner) AddBytes(data []byte) {
    38  	if len(data) > 0 {
    39  		j.lastByte = data[len(data)-1]
    40  	}
    41  	j.bytes = append(j.bytes, joinerBytes{data, j.length})
    42  	j.length += uint32(len(data))
    43  }
    44  
    45  func (j *Joiner) LastByte() byte {
    46  	return j.lastByte
    47  }
    48  
    49  func (j *Joiner) Length() uint32 {
    50  	return j.length
    51  }
    52  
    53  func (j *Joiner) EnsureNewlineAtEnd() {
    54  	if j.length > 0 && j.lastByte != '\n' {
    55  		j.AddString("\n")
    56  	}
    57  }
    58  
    59  func (j *Joiner) Done() []byte {
    60  	if len(j.strings) == 0 && len(j.bytes) == 1 && j.bytes[0].offset == 0 {
    61  		// No need to allocate if there was only a single byte array written
    62  		return j.bytes[0].data
    63  	}
    64  	buffer := make([]byte, j.length)
    65  	for _, item := range j.strings {
    66  		copy(buffer[item.offset:], item.data)
    67  	}
    68  	for _, item := range j.bytes {
    69  		copy(buffer[item.offset:], item.data)
    70  	}
    71  	return buffer
    72  }
    73  
    74  func (j *Joiner) Contains(s string, b []byte) bool {
    75  	for _, item := range j.strings {
    76  		if strings.Contains(item.data, s) {
    77  			return true
    78  		}
    79  	}
    80  	for _, item := range j.bytes {
    81  		if bytes.Contains(item.data, b) {
    82  			return true
    83  		}
    84  	}
    85  	return false
    86  }