74 lines
1.6 KiB
Go
74 lines
1.6 KiB
Go
package wordwrap
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import (
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"bytes"
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"unicode"
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)
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// WrapString wraps the given string within lim width in characters.
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//
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// Wrapping is currently naive and only happens at white-space. A future
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// version of the library will implement smarter wrapping. This means that
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// pathological cases can dramatically reach past the limit, such as a very
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// long word.
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func WrapString(s string, lim uint) string {
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// Initialize a buffer with a slightly larger size to account for breaks
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init := make([]byte, 0, len(s))
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buf := bytes.NewBuffer(init)
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var current uint
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var wordBuf, spaceBuf bytes.Buffer
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for _, char := range s {
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if char == '\n' {
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if wordBuf.Len() == 0 {
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if current+uint(spaceBuf.Len()) > lim {
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current = 0
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} else {
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current += uint(spaceBuf.Len())
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spaceBuf.WriteTo(buf)
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}
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spaceBuf.Reset()
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} else {
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current += uint(spaceBuf.Len() + wordBuf.Len())
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spaceBuf.WriteTo(buf)
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spaceBuf.Reset()
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wordBuf.WriteTo(buf)
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wordBuf.Reset()
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}
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buf.WriteRune(char)
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current = 0
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} else if unicode.IsSpace(char) {
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if spaceBuf.Len() == 0 || wordBuf.Len() > 0 {
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current += uint(spaceBuf.Len() + wordBuf.Len())
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spaceBuf.WriteTo(buf)
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spaceBuf.Reset()
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wordBuf.WriteTo(buf)
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wordBuf.Reset()
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}
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spaceBuf.WriteRune(char)
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} else {
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wordBuf.WriteRune(char)
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if current+uint(spaceBuf.Len()+wordBuf.Len()) > lim && uint(wordBuf.Len()) < lim {
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buf.WriteRune('\n')
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current = 0
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spaceBuf.Reset()
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}
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}
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}
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if wordBuf.Len() == 0 {
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if current+uint(spaceBuf.Len()) <= lim {
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spaceBuf.WriteTo(buf)
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}
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} else {
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spaceBuf.WriteTo(buf)
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wordBuf.WriteTo(buf)
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}
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return buf.String()
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}
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