Use a bytes.Buffer for shell_words string concat
It's much faster Signed-off-by: Daniel Nephin <dnephin@docker.com>
This commit is contained in:
Daniel Nephin
parent
df3c425407
commit
0055a48277
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@ -7,10 +7,12 @@ package dockerfile
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// be added by adding code to the "special ${} format processing" section
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import (
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"fmt"
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"bytes"
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"strings"
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"text/scanner"
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"unicode"
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"github.com/pkg/errors"
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)
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type shellWord struct {
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@ -105,7 +107,7 @@ func (w *wordsStruct) getWords() []string {
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// Process the word, starting at 'pos', and stop when we get to the
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// end of the word or the 'stopChar' character
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func (sw *shellWord) processStopOn(stopChar rune) (string, []string, error) {
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var result string
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var result bytes.Buffer
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var words wordsStruct
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var charFuncMapping = map[rune]func() (string, error){
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@ -127,7 +129,7 @@ func (sw *shellWord) processStopOn(stopChar rune) (string, []string, error) {
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if err != nil {
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return "", []string{}, err
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}
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result += tmp
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result.WriteString(tmp)
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if ch == rune('$') {
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words.addString(tmp)
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@ -140,7 +142,6 @@ func (sw *shellWord) processStopOn(stopChar rune) (string, []string, error) {
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if ch == sw.escapeToken {
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// '\' (default escape token, but ` allowed) escapes, except end of line
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ch = sw.scanner.Next()
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if ch == scanner.EOF {
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@ -152,11 +153,11 @@ func (sw *shellWord) processStopOn(stopChar rune) (string, []string, error) {
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words.addChar(ch)
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}
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result += string(ch)
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result.WriteRune(ch)
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}
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}
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return result, words.getWords(), nil
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return result.String(), words.getWords(), nil
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}
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func (sw *shellWord) processSingleQuote() (string, error) {
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@ -169,25 +170,20 @@ func (sw *shellWord) processSingleQuote() (string, error) {
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// all the characters (except single quotes, making it impossible to put
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// single-quotes in a single-quoted string).
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var result string
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var result bytes.Buffer
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sw.scanner.Next()
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for {
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ch := sw.scanner.Next()
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if ch == scanner.EOF {
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return "", fmt.Errorf("unexpected end of statement while looking for matching single-quote")
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switch ch {
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case scanner.EOF:
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return "", errors.New("unexpected end of statement while looking for matching single-quote")
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case '\'':
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return result.String(), nil
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}
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if ch == '\'' {
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break
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}
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result += string(ch)
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result.WriteRune(ch)
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}
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return result, nil
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}
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func (sw *shellWord) processDoubleQuote() (string, error) {
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@ -203,116 +199,107 @@ func (sw *shellWord) processDoubleQuote() (string, error) {
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// $ ` " \ <newline>.
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// Otherwise it remains literal.
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var result string
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var result bytes.Buffer
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sw.scanner.Next()
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for {
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ch := sw.scanner.Peek()
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if ch == scanner.EOF {
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return "", fmt.Errorf("unexpected end of statement while looking for matching double-quote")
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}
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if ch == '"' {
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switch sw.scanner.Peek() {
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case scanner.EOF:
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return "", errors.New("unexpected end of statement while looking for matching double-quote")
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case '"':
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sw.scanner.Next()
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break
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}
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if ch == '$' {
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tmp, err := sw.processDollar()
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return result.String(), nil
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case '$':
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value, err := sw.processDollar()
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if err != nil {
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return "", err
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}
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result += tmp
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} else {
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ch = sw.scanner.Next()
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result.WriteString(value)
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default:
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ch := sw.scanner.Next()
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if ch == sw.escapeToken {
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chNext := sw.scanner.Peek()
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if chNext == scanner.EOF {
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switch sw.scanner.Peek() {
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case scanner.EOF:
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// Ignore \ at end of word
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continue
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}
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// Note: for now don't do anything special with ` chars.
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// Not sure what to do with them anyway since we're not going
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// to execute the text in there (not now anyway).
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if chNext == '"' || chNext == '$' || chNext == sw.escapeToken {
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case '"', '$', sw.escapeToken:
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// These chars can be escaped, all other \'s are left as-is
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// Note: for now don't do anything special with ` chars.
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// Not sure what to do with them anyway since we're not going
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// to execute the text in there (not now anyway).
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ch = sw.scanner.Next()
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}
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}
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result += string(ch)
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result.WriteRune(ch)
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}
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}
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return result, nil
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}
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func (sw *shellWord) processDollar() (string, error) {
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sw.scanner.Next()
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ch := sw.scanner.Peek()
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if ch == '{' {
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sw.scanner.Next()
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name := sw.processName()
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ch = sw.scanner.Peek()
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if ch == '}' {
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// Normal ${xx} case
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sw.scanner.Next()
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return sw.getEnv(name), nil
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}
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if ch == ':' {
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// Special ${xx:...} format processing
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// Yes it allows for recursive $'s in the ... spot
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sw.scanner.Next() // skip over :
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modifier := sw.scanner.Next()
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word, _, err := sw.processStopOn('}')
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if err != nil {
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return "", err
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}
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// Grab the current value of the variable in question so we
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// can use to to determine what to do based on the modifier
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newValue := sw.getEnv(name)
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switch modifier {
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case '+':
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if newValue != "" {
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newValue = word
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}
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return newValue, nil
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case '-':
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if newValue == "" {
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newValue = word
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}
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return newValue, nil
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default:
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return "", fmt.Errorf("Unsupported modifier (%c) in substitution: %s", modifier, sw.word)
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}
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}
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return "", fmt.Errorf("Missing ':' in substitution: %s", sw.word)
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}
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// $xxx case
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name := sw.processName()
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if name == "" {
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return "$", nil
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if sw.scanner.Peek() != '{' {
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name := sw.processName()
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if name == "" {
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return "$", nil
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}
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return sw.getEnv(name), nil
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}
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return sw.getEnv(name), nil
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sw.scanner.Next()
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name := sw.processName()
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ch := sw.scanner.Peek()
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if ch == '}' {
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// Normal ${xx} case
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sw.scanner.Next()
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return sw.getEnv(name), nil
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}
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if ch == ':' {
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// Special ${xx:...} format processing
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// Yes it allows for recursive $'s in the ... spot
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sw.scanner.Next() // skip over :
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modifier := sw.scanner.Next()
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word, _, err := sw.processStopOn('}')
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if err != nil {
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return "", err
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}
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// Grab the current value of the variable in question so we
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// can use to to determine what to do based on the modifier
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newValue := sw.getEnv(name)
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switch modifier {
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case '+':
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if newValue != "" {
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newValue = word
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}
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return newValue, nil
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case '-':
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if newValue == "" {
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newValue = word
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}
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return newValue, nil
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default:
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return "", errors.Errorf("unsupported modifier (%c) in substitution: %s", modifier, sw.word)
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}
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}
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return "", errors.Errorf("missing ':' in substitution: %s", sw.word)
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}
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func (sw *shellWord) processName() string {
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// Read in a name (alphanumeric or _)
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// If it starts with a numeric then just return $#
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var name string
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var name bytes.Buffer
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for sw.scanner.Peek() != scanner.EOF {
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ch := sw.scanner.Peek()
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if len(name) == 0 && unicode.IsDigit(ch) {
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if name.Len() == 0 && unicode.IsDigit(ch) {
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ch = sw.scanner.Next()
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return string(ch)
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}
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@ -320,10 +307,10 @@ func (sw *shellWord) processName() string {
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break
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}
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ch = sw.scanner.Next()
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name += string(ch)
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name.WriteRune(ch)
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}
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return name
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return name.String()
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}
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func (sw *shellWord) getEnv(name string) string {
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