parseForSystemTimeClause parses the FOR SYSTEM_TIME clause that follows a table reference. The caller has already consumed FOR.
()
| 262 | // parseForSystemTimeClause parses the FOR SYSTEM_TIME clause that follows a table reference. |
| 263 | // The caller has already consumed FOR. |
| 264 | func (p *Parser) parseForSystemTimeClause() (*ast.ForSystemTimeClause, error) { |
| 265 | if !strings.EqualFold(p.currentToken.Token.Value, "SYSTEM_TIME") { |
| 266 | return nil, fmt.Errorf("expected SYSTEM_TIME after FOR, got %q", p.currentToken.Token.Value) |
| 267 | } |
| 268 | sysTimePos := p.currentLocation() // position of SYSTEM_TIME token |
| 269 | p.advance() |
| 270 | |
| 271 | clause := &ast.ForSystemTimeClause{} |
| 272 | clause.Pos = sysTimePos |
| 273 | word := strings.ToUpper(p.currentToken.Token.Value) |
| 274 | |
| 275 | switch word { |
| 276 | case "AS": |
| 277 | p.advance() |
| 278 | if !strings.EqualFold(p.currentToken.Token.Value, "OF") { |
| 279 | return nil, fmt.Errorf("expected OF after AS, got %q", p.currentToken.Token.Value) |
| 280 | } |
| 281 | p.advance() |
| 282 | expr, err := p.parseTemporalPointExpression() |
| 283 | if err != nil { |
| 284 | return nil, err |
| 285 | } |
| 286 | clause.Type = ast.SystemTimeAsOf |
| 287 | clause.Point = expr |
| 288 | case "BETWEEN": |
| 289 | p.advance() |
| 290 | // Use parsePrimaryExpression to avoid consuming AND as a binary logical operator. |
| 291 | start, err := p.parseTemporalPointExpression() |
| 292 | if err != nil { |
| 293 | return nil, err |
| 294 | } |
| 295 | if !strings.EqualFold(p.currentToken.Token.Value, "AND") { |
| 296 | return nil, fmt.Errorf("expected AND in FOR SYSTEM_TIME BETWEEN, got %q", p.currentToken.Token.Value) |
| 297 | } |
| 298 | p.advance() |
| 299 | end, err := p.parseTemporalPointExpression() |
| 300 | if err != nil { |
| 301 | return nil, err |
| 302 | } |
| 303 | clause.Type = ast.SystemTimeBetween |
| 304 | clause.Start = start |
| 305 | clause.End = end |
| 306 | case "FROM": |
| 307 | p.advance() |
| 308 | start, err := p.parseTemporalPointExpression() |
| 309 | if err != nil { |
| 310 | return nil, err |
| 311 | } |
| 312 | if !strings.EqualFold(p.currentToken.Token.Value, "TO") { |
| 313 | return nil, fmt.Errorf("expected TO in FOR SYSTEM_TIME FROM, got %q", p.currentToken.Token.Value) |
| 314 | } |
| 315 | p.advance() |
| 316 | end, err := p.parseTemporalPointExpression() |
| 317 | if err != nil { |
| 318 | return nil, err |
| 319 | } |
| 320 | clause.Type = ast.SystemTimeFromTo |
| 321 | clause.Start = start |
no test coverage detected