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buildx/vendor/github.com/compose-spec/godotenv/parser.go

224 lines
4.9 KiB
Go

package godotenv
import (
"bytes"
"errors"
"fmt"
"strings"
"unicode"
)
const (
charComment = '#'
prefixSingleQuote = '\''
prefixDoubleQuote = '"'
exportPrefix = "export"
)
func parseBytes(src []byte, out map[string]string, lookupFn LookupFn) error {
cutset := src
for {
cutset = getStatementStart(cutset)
if cutset == nil {
// reached end of file
break
}
key, left, inherited, err := locateKeyName(cutset)
if err != nil {
return err
}
if strings.Contains(key, " ") {
return errors.New("key cannot contain a space")
}
if inherited {
if lookupFn == nil {
lookupFn = noLookupFn
}
value, ok := lookupFn(key)
if ok {
out[key] = value
cutset = left
continue
}
}
value, left, err := extractVarValue(left, out, lookupFn)
if err != nil {
return err
}
out[key] = value
cutset = left
}
return nil
}
// getStatementPosition returns position of statement begin.
//
// It skips any comment line or non-whitespace character.
func getStatementStart(src []byte) []byte {
pos := indexOfNonSpaceChar(src)
if pos == -1 {
return nil
}
src = src[pos:]
if src[0] != charComment {
return src
}
// skip comment section
pos = bytes.IndexFunc(src, isCharFunc('\n'))
if pos == -1 {
return nil
}
return getStatementStart(src[pos:])
}
// locateKeyName locates and parses key name and returns rest of slice
func locateKeyName(src []byte) (key string, cutset []byte, inherited bool, err error) {
// trim "export" and space at beginning
src = bytes.TrimLeftFunc(bytes.TrimPrefix(src, []byte(exportPrefix)), isSpace)
// locate key name end and validate it in single loop
offset := 0
loop:
for i, char := range src {
rchar := rune(char)
if isSpace(rchar) {
continue
}
switch char {
case '=', ':', '\n':
// library also supports yaml-style value declaration
key = string(src[0:i])
offset = i + 1
inherited = char == '\n'
break loop
case '_':
default:
// variable name should match [A-Za-z0-9_]
if unicode.IsLetter(rchar) || unicode.IsNumber(rchar) {
continue
}
return "", nil, inherited, fmt.Errorf(
`unexpected character %q in variable name near %q`,
string(char), string(src))
}
}
if len(src) == 0 {
return "", nil, inherited, errors.New("zero length string")
}
// trim whitespace
key = strings.TrimRightFunc(key, unicode.IsSpace)
cutset = bytes.TrimLeftFunc(src[offset:], isSpace)
return key, cutset, inherited, nil
}
// extractVarValue extracts variable value and returns rest of slice
func extractVarValue(src []byte, envMap map[string]string, lookupFn LookupFn) (value string, rest []byte, err error) {
quote, hasPrefix := hasQuotePrefix(src)
if !hasPrefix {
// unquoted value - read until whitespace
end := bytes.IndexFunc(src, unicode.IsSpace)
if end == -1 {
return expandVariables(string(src), envMap, lookupFn), nil, nil
}
return expandVariables(string(src[0:end]), envMap, lookupFn), src[end:], nil
}
// lookup quoted string terminator
for i := 1; i < len(src); i++ {
if char := src[i]; char != quote {
continue
}
// skip escaped quote symbol (\" or \', depends on quote)
if prevChar := src[i-1]; prevChar == '\\' {
continue
}
// trim quotes
trimFunc := isCharFunc(rune(quote))
value = string(bytes.TrimLeftFunc(bytes.TrimRightFunc(src[0:i], trimFunc), trimFunc))
if quote == prefixDoubleQuote {
// unescape newlines for double quote (this is compat feature)
// and expand environment variables
value = expandVariables(expandEscapes(value), envMap, lookupFn)
}
return value, src[i+1:], nil
}
// return formatted error if quoted string is not terminated
valEndIndex := bytes.IndexFunc(src, isCharFunc('\n'))
if valEndIndex == -1 {
valEndIndex = len(src)
}
return "", nil, fmt.Errorf("unterminated quoted value %s", src[:valEndIndex])
}
func expandEscapes(str string) string {
out := escapeRegex.ReplaceAllStringFunc(str, func(match string) string {
c := strings.TrimPrefix(match, `\`)
switch c {
case "n":
return "\n"
case "r":
return "\r"
default:
return match
}
})
return unescapeCharsRegex.ReplaceAllString(out, "$1")
}
func indexOfNonSpaceChar(src []byte) int {
return bytes.IndexFunc(src, func(r rune) bool {
return !unicode.IsSpace(r)
})
}
// hasQuotePrefix reports whether charset starts with single or double quote and returns quote character
func hasQuotePrefix(src []byte) (prefix byte, isQuored bool) {
if len(src) == 0 {
return 0, false
}
switch prefix := src[0]; prefix {
case prefixDoubleQuote, prefixSingleQuote:
return prefix, true
default:
return 0, false
}
}
func isCharFunc(char rune) func(rune) bool {
return func(v rune) bool {
return v == char
}
}
// isSpace reports whether the rune is a space character but not line break character
//
// this differs from unicode.IsSpace, which also applies line break as space
func isSpace(r rune) bool {
switch r {
case '\t', '\v', '\f', '\r', ' ', 0x85, 0xA0:
return true
}
return false
}