115 lines
2.5 KiB
Go
115 lines
2.5 KiB
Go
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package squirrel
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import (
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"bytes"
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"fmt"
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"strings"
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)
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// PlaceholderFormat is the interface that wraps the ReplacePlaceholders method.
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//
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// ReplacePlaceholders takes a SQL statement and replaces each question mark
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// placeholder with a (possibly different) SQL placeholder.
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type PlaceholderFormat interface {
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ReplacePlaceholders(sql string) (string, error)
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}
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type placeholderDebugger interface {
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debugPlaceholder() string
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}
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var (
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// Question is a PlaceholderFormat instance that leaves placeholders as
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// question marks.
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Question = questionFormat{}
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// Dollar is a PlaceholderFormat instance that replaces placeholders with
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// dollar-prefixed positional placeholders (e.g. $1, $2, $3).
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Dollar = dollarFormat{}
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// Colon is a PlaceholderFormat instance that replaces placeholders with
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// colon-prefixed positional placeholders (e.g. :1, :2, :3).
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Colon = colonFormat{}
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// AtP is a PlaceholderFormat instance that replaces placeholders with
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// "@p"-prefixed positional placeholders (e.g. @p1, @p2, @p3).
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AtP = atpFormat{}
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)
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type questionFormat struct{}
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func (questionFormat) ReplacePlaceholders(sql string) (string, error) {
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return sql, nil
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}
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func (questionFormat) debugPlaceholder() string {
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return "?"
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}
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type dollarFormat struct{}
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func (dollarFormat) ReplacePlaceholders(sql string) (string, error) {
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return replacePositionalPlaceholders(sql, "$")
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}
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func (dollarFormat) debugPlaceholder() string {
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return "$"
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}
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type colonFormat struct{}
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func (colonFormat) ReplacePlaceholders(sql string) (string, error) {
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return replacePositionalPlaceholders(sql, ":")
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}
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func (colonFormat) debugPlaceholder() string {
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return ":"
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}
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type atpFormat struct{}
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func (atpFormat) ReplacePlaceholders(sql string) (string, error) {
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return replacePositionalPlaceholders(sql, "@p")
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}
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func (atpFormat) debugPlaceholder() string {
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return "@p"
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}
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// Placeholders returns a string with count ? placeholders joined with commas.
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func Placeholders(count int) string {
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if count < 1 {
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return ""
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}
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return strings.Repeat(",?", count)[1:]
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}
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func replacePositionalPlaceholders(sql, prefix string) (string, error) {
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buf := &bytes.Buffer{}
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i := 0
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for {
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p := strings.Index(sql, "?")
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if p == -1 {
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break
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}
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if len(sql[p:]) > 1 && sql[p:p+2] == "??" { // escape ?? => ?
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buf.WriteString(sql[:p])
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buf.WriteString("?")
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if len(sql[p:]) == 1 {
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break
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}
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sql = sql[p+2:]
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} else {
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i++
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buf.WriteString(sql[:p])
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fmt.Fprintf(buf, "%s%d", prefix, i)
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sql = sql[p+1:]
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}
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}
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buf.WriteString(sql)
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return buf.String(), nil
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}
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