mirror of https://github.com/prometheus/prometheus
64 lines
1.8 KiB
Go
64 lines
1.8 KiB
Go
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package casing
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// Camel returns the CamelCased name.
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//
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// This was moved from the now deprecated github.com/golang/protobuf/protoc-gen-go/generator package
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//
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// If there is an interior underscore followed by a lower case letter,
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// drop the underscore and convert the letter to upper case.
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// There is a remote possibility of this rewrite causing a name collision,
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// but it's so remote we're prepared to pretend it's nonexistent - since the
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// C++ generator lowercases names, it's extremely unlikely to have two fields
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// with different capitalizations.
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// In short, _my_field_name_2 becomes XMyFieldName_2.
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func Camel(s string) string {
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if s == "" {
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return ""
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}
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t := make([]byte, 0, 32)
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i := 0
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if s[0] == '_' {
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// Need a capital letter; drop the '_'.
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t = append(t, 'X')
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i++
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}
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// Invariant: if the next letter is lower case, it must be converted
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// to upper case.
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// That is, we process a word at a time, where words are marked by _ or
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// upper case letter. Digits are treated as words.
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for ; i < len(s); i++ {
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c := s[i]
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if c == '_' && i+1 < len(s) && isASCIILower(s[i+1]) {
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continue // Skip the underscore in s.
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}
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if isASCIIDigit(c) {
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t = append(t, c)
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continue
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}
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// Assume we have a letter now - if not, it's a bogus identifier.
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// The next word is a sequence of characters that must start upper case.
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if isASCIILower(c) {
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c ^= ' ' // Make it a capital letter.
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}
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t = append(t, c) // Guaranteed not lower case.
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// Accept lower case sequence that follows.
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for i+1 < len(s) && isASCIILower(s[i+1]) {
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i++
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t = append(t, s[i])
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}
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}
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return string(t)
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}
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// And now lots of helper functions.
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// Is c an ASCII lower-case letter?
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func isASCIILower(c byte) bool {
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return 'a' <= c && c <= 'z'
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}
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// Is c an ASCII digit?
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func isASCIIDigit(c byte) bool {
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return '0' <= c && c <= '9'
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}
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