40 lines
1.2 KiB
Go
40 lines
1.2 KiB
Go
package grammar
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import (
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"encoding/json"
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"fmt"
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"strings"
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)
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func IsTemplate(arg string) (bool, error) {
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if strings.ContainsRune(arg, '{') || (isJSONStart(strings.TrimSpace(arg)) && json.Valid([]byte(arg))) {
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return true, nil
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}
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if i := strings.IndexAny(arg, `}"`); i >= 0 {
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return false, fmt.Errorf("%q holds a %q, which no path may, and it is not valid JSON, so it names no template either", arg, arg[i:i+1])
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}
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if strings.HasPrefix(strings.TrimSpace(arg), "[") {
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return false, fmt.Errorf(`%q starts with "[" and is not valid JSON, so it names no template; a path starts with a name`, arg)
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}
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path, err := CallerPath(arg)
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if err != nil {
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return false, err
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}
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_, err = SplitPath(path)
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return false, err
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}
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// CallerPath is a path as a caller passed it, without the one / it may start with, as a
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// reference does.
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func CallerPath(path string) (string, error) {
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rest := strings.TrimPrefix(path, "/")
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if strings.HasPrefix(rest, "/") {
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return "", fmt.Errorf("path %s starts with more than one /; write /%s", path, strings.TrimLeft(rest, "/"))
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}
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return rest, nil
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}
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func isJSONStart(arg string) bool {
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return strings.HasPrefix(arg, "[") || strings.HasPrefix(arg, `"`)
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}
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