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repls.go
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repls.go
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package ustr
import (
"strings"
)
// ReplB replaces individual `byte`s in `s` based on the given old-new pairs: because
// for some few `strings.Replace` / `strings.Replacer` scenarios, nothing more is needed.
func ReplB(s string, oldNew ...byte) string {
var buf strings.Builder
start := 0
for i, l, n := 0, len(s), len(oldNew)-1; i < l; i++ {
for j := 0; j < n; j += 2 {
if s[i] == oldNew[j] {
buf.WriteString(s[start:i])
buf.WriteByte(oldNew[j+1])
start = i + 1
break
}
}
}
if start > 0 {
buf.WriteString(s[start:])
}
if buf.Len() > 0 {
return buf.String()
}
return s
}
// NamedPlaceholders is an occasionally-preferable alternative to `fmt.Sprintf` or
// `strings.Replace` / `strings.Replacer` for (fully `string`ly-typed) "micro-templating":
//
// ```go
// repl := ustr.NamedPlaceHolders('(', ']')
// hi := repl("Hello (name]!", "name", "world")
// ```
//
//
// The delimiter `begin` and `end` chars may well be equal, if so desired. When
// called, the returned `func` traverses its `string` arg exactly once, ie. it
// does not re-process the replacements or its final result. It searches through
// its name-value-pairs once per fully-delimited-substring. Any of those occurrences
// not found in its name-value-pairs are left in-place including the delimiters.
func NamedPlaceholders(begin byte, end byte) func(string, ...string) string {
return func(s string, namesAndValues ...string) string {
if len(s) >= 3 && len(namesAndValues) > 1 {
var buf strings.Builder
start, pos := 0, -1
for i := 0; i < len(s); i++ {
if s[i] == begin {
pos = i
} else if s[i] == end && pos >= 0 {
nidx, name := -1, s[pos+1:i]
for j := 0; j < len(namesAndValues); j += 2 {
if namesAndValues[j] == name {
nidx = j
break
}
}
if nidx >= 0 && nidx < len(namesAndValues)-1 {
buf.WriteString(s[start:pos])
buf.WriteString(namesAndValues[nidx+1])
start = i + 1
} else {
pos = -1
}
}
}
if start > 0 {
buf.WriteString(s[start:])
}
if buf.Len() > 0 {
return buf.String()
}
}
return s
}
}