3eac3cd8cb
- Ensures MySQL compatibility by always providing a LIMIT when OFFSET is used - Updates tests to reflect new behavior - Improves code organization and documentation
70 lines
1.5 KiB
Go
70 lines
1.5 KiB
Go
package clause
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import (
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"math"
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)
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// Limit represents a limit clause
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type Limit struct {
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Limit *int
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Offset int
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}
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// Name returns the name of the clause ("LIMIT")
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func (limit Limit) Name() string {
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return "LIMIT"
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}
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// Build constructs the LIMIT clause
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func (limit Limit) Build(builder Builder) {
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// NOT: We don't auto-set limit here. We only rely on the final struct's Limit and Offset.
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// Any "auto offset => limit" logic is handled in MergeClause.
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if limit.Limit != nil && *limit.Limit >= 0 {
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builder.WriteString("LIMIT ")
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builder.AddVar(builder, *limit.Limit)
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}
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if limit.Offset > 0 {
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// Add space if LIMIT was set
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if limit.Limit != nil && *limit.Limit >= 0 {
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builder.WriteByte(' ')
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}
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builder.WriteString("OFFSET ")
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builder.AddVar(builder, limit.Offset)
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}
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}
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// MergeClause merges two limit clauses
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func (limit Limit) MergeClause(clause *Clause) {
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clause.Name = ""
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if v, ok := clause.Expression.(Limit); ok {
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// 1) Merge offset
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if limit.Offset == 0 && v.Offset > 0 {
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limit.Offset = v.Offset
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} else if limit.Offset < 0 {
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// Negative offset => 0
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limit.Offset = 0
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}
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// 2) Merge limit
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if (limit.Limit == nil || *limit.Limit == 0) && v.Limit != nil {
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limit.Limit = v.Limit
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}
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// 3) If final limit is negative => treat it as nil (meaning "no limit")
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if limit.Limit != nil && *limit.Limit < 0 {
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limit.Limit = nil
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}
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}
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// 4) If offset > 0 but limit is still nil, set limit to math.MaxInt
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if limit.Offset > 0 && limit.Limit == nil {
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maxInt := math.MaxInt
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limit.Limit = &maxInt
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}
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clause.Expression = limit
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}
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