warkanum
9cc10715e3
- mssql: write computed columns (AS (expr) PERSISTED) and identity; read computed definition and identity - sqlite: write GENERATED ALWAYS AS (expr) STORED; read generated columns via table_xinfo and parse the expression - drizzle: generatedAlwaysAs / generated(Always|ByDefault)AsIdentity, read and write - typeorm: asExpression/generatedType and identity decorators, read and write; decorator scan is now quote-aware - bun, gorm readers: read generated and identity markers - readmes updated
117 lines
2.4 KiB
Go
117 lines
2.4 KiB
Go
package sqlite
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import (
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"regexp"
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"strings"
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)
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var generatedAsRegex = regexp.MustCompile(`(?is)\bAS\s*\(`)
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// parseGeneratedExpression extracts the expression of a generated column from a CREATE
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// TABLE statement, e.g. `full TEXT GENERATED ALWAYS AS (a || b) STORED` yields `a || b`.
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// It returns "" when the column or its expression cannot be found.
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func parseGeneratedExpression(createSQL, columnName string) string {
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open := strings.Index(createSQL, "(")
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if open < 0 {
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return ""
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}
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for _, def := range splitTopLevel(createSQL[open+1:]) {
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if !strings.EqualFold(firstIdentifier(def), columnName) {
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continue
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}
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loc := generatedAsRegex.FindStringIndex(def)
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if loc == nil {
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return ""
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}
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return balancedParens(def[loc[1]-1:])
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}
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return ""
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}
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// splitTopLevel splits a table body on commas that are outside parentheses and quotes,
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// stopping at the parenthesis that closes the body.
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func splitTopLevel(body string) []string {
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var parts []string
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depth := 0
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var quote byte
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start := 0
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for i := 0; i < len(body); i++ {
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ch := body[i]
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if quote != 0 {
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if ch == quote {
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quote = 0
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}
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continue
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}
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switch ch {
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case '\'', '"', '`':
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quote = ch
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case '[':
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quote = ']'
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case '(':
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depth++
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case ')':
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if depth == 0 {
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return append(parts, body[start:i])
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}
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depth--
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case ',':
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if depth == 0 {
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parts = append(parts, body[start:i])
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start = i + 1
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}
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}
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}
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return append(parts, body[start:])
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}
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// firstIdentifier returns the first (possibly quoted) identifier of a column definition.
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func firstIdentifier(def string) string {
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def = strings.TrimSpace(def)
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if def == "" {
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return ""
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}
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switch def[0] {
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case '"', '\'', '`':
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if end := strings.IndexByte(def[1:], def[0]); end >= 0 {
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return def[1 : 1+end]
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}
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case '[':
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if end := strings.IndexByte(def, ']'); end >= 0 {
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return def[1:end]
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}
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}
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if end := strings.IndexAny(def, " \t\r\n"); end >= 0 {
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return def[:end]
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}
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return def
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}
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// balancedParens returns the text inside the parenthesis group that starts at s[0].
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func balancedParens(s string) string {
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depth := 0
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var quote byte
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for i := 0; i < len(s); i++ {
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ch := s[i]
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if quote != 0 {
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if ch == quote {
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quote = 0
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}
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continue
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}
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switch ch {
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case '\'', '"':
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quote = ch
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case '(':
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depth++
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case ')':
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depth--
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if depth == 0 {
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return strings.TrimSpace(s[1:i])
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}
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}
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}
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return ""
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}
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