61 lines
1.2 KiB
Go
61 lines
1.2 KiB
Go
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package exql
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import (
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"git.hexq.cn/tiglog/mydb/internal/cache"
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)
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// GroupBy represents a SQL's "group by" statement.
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type GroupBy struct {
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Columns Fragment
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}
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var _ = Fragment(&GroupBy{})
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type groupByT struct {
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GroupColumns string
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}
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// Hash returns a unique identifier.
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func (g *GroupBy) Hash() uint64 {
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if g == nil {
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return cache.NewHash(FragmentType_GroupBy, nil)
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}
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return cache.NewHash(FragmentType_GroupBy, g.Columns)
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}
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// GroupByColumns creates and returns a GroupBy with the given column.
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func GroupByColumns(columns ...Fragment) *GroupBy {
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return &GroupBy{Columns: JoinColumns(columns...)}
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}
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func (g *GroupBy) IsEmpty() bool {
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if g == nil || g.Columns == nil {
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return true
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}
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return g.Columns.(hasIsEmpty).IsEmpty()
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}
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// Compile transforms the GroupBy into an equivalent SQL representation.
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func (g *GroupBy) Compile(layout *Template) (compiled string, err error) {
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if c, ok := layout.Read(g); ok {
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return c, nil
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}
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if g.Columns != nil {
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columns, err := g.Columns.Compile(layout)
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if err != nil {
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return "", err
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}
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data := groupByT{
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GroupColumns: columns,
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}
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compiled = layout.MustCompile(layout.GroupByLayout, data)
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}
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layout.Write(g, compiled)
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return
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}
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