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152 lines
2.6 KiB
152 lines
2.6 KiB
package exql
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import (
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"strings"
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)
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// isBlankSymbol returns true if the given byte is either space, tab, carriage
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// return or newline.
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func isBlankSymbol(in byte) bool {
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return in == ' ' || in == '\t' || in == '\r' || in == '\n'
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}
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// trimString returns a slice of s with a leading and trailing blank symbols
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// (as defined by isBlankSymbol) removed.
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func trimString(s string) string {
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// This conversion is rather slow.
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// return string(trimBytes([]byte(s)))
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start, end := 0, len(s)-1
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if end < start {
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return ""
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}
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for isBlankSymbol(s[start]) {
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start++
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if start >= end {
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return ""
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}
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}
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for isBlankSymbol(s[end]) {
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end--
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}
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return s[start : end+1]
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}
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// trimBytes returns a slice of s with a leading and trailing blank symbols (as
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// defined by isBlankSymbol) removed.
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func trimBytes(s []byte) []byte {
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start, end := 0, len(s)-1
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if end < start {
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return []byte{}
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}
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for isBlankSymbol(s[start]) {
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start++
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if start >= end {
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return []byte{}
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}
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}
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for isBlankSymbol(s[end]) {
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end--
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}
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return s[start : end+1]
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}
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/*
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// Separates by a comma, ignoring spaces too.
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// This was slower than strings.Split.
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func separateByComma(in string) (out []string) {
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out = []string{}
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start, lim := 0, len(in)-1
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for start < lim {
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var end int
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for end = start; end <= lim; end++ {
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// Is a comma?
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if in[end] == ',' {
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break
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}
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}
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out = append(out, trimString(in[start:end]))
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start = end + 1
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}
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return
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}
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*/
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// Separates by a comma, ignoring spaces too.
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func separateByComma(in string) (out []string) {
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out = strings.Split(in, ",")
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for i := range out {
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out[i] = trimString(out[i])
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}
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return
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}
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// Separates by spaces, ignoring spaces too.
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func separateBySpace(in string) (out []string) {
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if len(in) == 0 {
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return []string{""}
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}
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pre := strings.Split(in, " ")
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out = make([]string, 0, len(pre))
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for i := range pre {
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pre[i] = trimString(pre[i])
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if pre[i] != "" {
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out = append(out, pre[i])
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}
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}
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return
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}
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func separateByAS(in string) (out []string) {
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out = []string{}
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if len(in) < 6 {
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// The minimum expression with the AS keyword is "x AS y", 6 chars.
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return []string{in}
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}
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start, lim := 0, len(in)-1
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for start <= lim {
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var end int
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for end = start; end <= lim; end++ {
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if end > 3 && isBlankSymbol(in[end]) && isBlankSymbol(in[end-3]) {
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if (in[end-1] == 's' || in[end-1] == 'S') && (in[end-2] == 'a' || in[end-2] == 'A') {
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break
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}
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}
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}
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if end < lim {
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out = append(out, trimString(in[start:end-3]))
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} else {
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out = append(out, trimString(in[start:end]))
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}
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start = end + 1
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}
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return
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}
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