82 lines
1.6 KiB
Go
82 lines
1.6 KiB
Go
package metrics
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import (
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"fmt"
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"regexp"
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"strings"
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)
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func validateMetric(s string) error {
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if len(s) == 0 {
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return fmt.Errorf("metric cannot be empty")
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}
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if s[0] == 0 {
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// Skip special case metrics. See Histogram for details.
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return nil
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}
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n := strings.IndexByte(s, '{')
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if n < 0 {
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return validateIdent(s)
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}
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ident := s[:n]
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s = s[n+1:]
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if err := validateIdent(ident); err != nil {
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return err
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}
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if len(s) == 0 || s[len(s)-1] != '}' {
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return fmt.Errorf("missing closing curly brace at the end of %q", ident)
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}
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return validateTags(s[:len(s)-1])
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}
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func validateTags(s string) error {
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if len(s) == 0 {
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return nil
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}
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for {
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n := strings.IndexByte(s, '=')
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if n < 0 {
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return fmt.Errorf("missing `=` after %q", s)
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}
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ident := s[:n]
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s = s[n+1:]
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if err := validateIdent(ident); err != nil {
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return err
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}
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if len(s) == 0 || s[0] != '"' {
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return fmt.Errorf("missing starting `\"` for %q value; tail=%q", ident, s)
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}
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s = s[1:]
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again:
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n = strings.IndexByte(s, '"')
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if n < 0 {
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return fmt.Errorf("missing trailing `\"` for %q value; tail=%q", ident, s)
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}
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m := n
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for m > 0 && s[m-1] == '\\' {
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m--
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}
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if (n-m)%2 == 1 {
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s = s[n+1:]
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goto again
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}
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s = s[n+1:]
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if len(s) == 0 {
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return nil
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}
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if !strings.HasPrefix(s, ", ") {
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return fmt.Errorf("missing `, ` after %q value; tail=%q", ident, s)
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}
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s = s[2:]
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}
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}
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func validateIdent(s string) error {
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if !identRegexp.MatchString(s) {
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return fmt.Errorf("invalid identifier %q", s)
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}
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return nil
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}
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var identRegexp = regexp.MustCompile("^[a-zA-Z_:][a-zA-Z0-9_:]*$")
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