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// Package js minifies ECMAScript5.1 following the specifications at http://www.ecma-international.org/ecma-262/5.1/.
package js // import "github.com/tdewolff/minify/js"
import (
"io"
"github.com/tdewolff/minify"
"github.com/tdewolff/parse"
"github.com/tdewolff/parse/js"
)
var (
spaceBytes = []byte(" ")
newlineBytes = []byte("\n")
)
////////////////////////////////////////////////////////////////
// DefaultMinifier is the default minifier.
var DefaultMinifier = &Minifier{}
// Minifier is a JS minifier.
type Minifier struct{}
// Minify minifies JS data, it reads from r and writes to w.
func Minify(m *minify.M, w io.Writer, r io.Reader, params map[string]string) error {
return DefaultMinifier.Minify(m, w, r, params)
}
// Minify minifies JS data, it reads from r and writes to w.
func (o *Minifier) Minify(_ *minify.M, w io.Writer, r io.Reader, _ map[string]string) error {
prev := js.LineTerminatorToken
prevLast := byte(' ')
lineTerminatorQueued := false
whitespaceQueued := false
l := js.NewLexer(r)
defer l.Restore()
for {
tt, data := l.Next()
if tt == js.ErrorToken {
if l.Err() != io.EOF {
return l.Err()
}
return nil
} else if tt == js.LineTerminatorToken {
lineTerminatorQueued = true
} else if tt == js.WhitespaceToken {
whitespaceQueued = true
} else if tt == js.SingleLineCommentToken || tt == js.MultiLineCommentToken {
if len(data) > 5 && data[1] == '*' && data[2] == '!' {
if _, err := w.Write(data[:3]); err != nil {
return err
}
comment := parse.ReplaceMultipleWhitespace(data[3 : len(data)-2])
if tt != js.MultiLineCommentToken {
// don't trim newlines in multiline comments as that might change ASI
// (we could do a more expensive check post-factum but it's not worth it)
comment = parse.TrimWhitespace(comment)
}
if _, err := w.Write(comment); err != nil {
return err
}
if _, err := w.Write(data[len(data)-2:]); err != nil {
return err
}
} else if tt == js.MultiLineCommentToken {
lineTerminatorQueued = true
} else {
whitespaceQueued = true
}
} else {
first := data[0]
if (prev == js.IdentifierToken || prev == js.NumericToken || prev == js.PunctuatorToken || prev == js.StringToken || prev == js.TemplateToken || prev == js.RegexpToken) &&
(tt == js.IdentifierToken || tt == js.NumericToken || tt == js.StringToken || tt == js.TemplateToken || tt == js.PunctuatorToken || tt == js.RegexpToken) {
if lineTerminatorQueued && (prev != js.PunctuatorToken || prevLast == '}' || prevLast == ']' || prevLast == ')' || prevLast == '+' || prevLast == '-' || prevLast == '"' || prevLast == '\'') &&
(tt != js.PunctuatorToken || first == '{' || first == '[' || first == '(' || first == '+' || first == '-' || first == '!' || first == '~') {
if _, err := w.Write(newlineBytes); err != nil {
return err
}
} else if whitespaceQueued && (prev != js.StringToken && prev != js.PunctuatorToken && tt != js.PunctuatorToken || (prevLast == '+' || prevLast == '-' || prevLast == '/') && first == prevLast) {
if _, err := w.Write(spaceBytes); err != nil {
return err
}
}
}
if _, err := w.Write(data); err != nil {
return err
}
prev = tt
prevLast = data[len(data)-1]
lineTerminatorQueued = false
whitespaceQueued = false
}
}
}
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