init - add project files

tools/jet-2.12.0/internal/jet/window_func.go

@@ -0,0 +1,186 @@
+package jet
+
+// Window interface
+type Window interface {
+	Serializer
+	ORDER_BY(expr ...OrderByClause) Window
+	ROWS(start FrameExtent, end ...FrameExtent) Window
+	RANGE(start FrameExtent, end ...FrameExtent) Window
+	GROUPS(start FrameExtent, end ...FrameExtent) Window
+}
+
+type windowImpl struct {
+	partitionBy []Expression
+	orderBy     ClauseOrderBy
+	frameUnits  string
+	start, end  FrameExtent
+
+	parent Window
+}
+
+func newWindowImpl(parent Window) *windowImpl {
+	newWindow := &windowImpl{}
+	if parent == nil {
+		newWindow.parent = newWindow
+	} else {
+		newWindow.parent = parent
+	}
+
+	return newWindow
+}
+
+func (w *windowImpl) serialize(statement StatementType, out *SQLBuilder, options ...SerializeOption) {
+	if !contains(options, NoWrap) {
+		out.WriteByte('(')
+	}
+
+	if w.partitionBy != nil {
+		out.WriteString("PARTITION BY")
+
+		serializeExpressionList(statement, w.partitionBy, ", ", out)
+	}
+	w.orderBy.SkipNewLine = true
+	w.orderBy.Serialize(statement, out, FallTrough(options)...)
+
+	if w.frameUnits != "" {
+		out.WriteString(w.frameUnits)
+
+		if w.end == nil {
+			w.start.serialize(statement, out)
+		} else {
+			out.WriteString("BETWEEN")
+			w.start.serialize(statement, out)
+			out.WriteString("AND")
+			w.end.serialize(statement, out)
+		}
+	}
+
+	if !contains(options, NoWrap) {
+		out.WriteByte(')')
+	}
+}
+
+func (w *windowImpl) ORDER_BY(exprs ...OrderByClause) Window {
+	w.orderBy.List = exprs
+	return w.parent
+}
+
+func (w *windowImpl) ROWS(start FrameExtent, end ...FrameExtent) Window {
+	w.frameUnits = "ROWS"
+	w.setFrameRange(start, end...)
+	return w.parent
+}
+
+func (w *windowImpl) RANGE(start FrameExtent, end ...FrameExtent) Window {
+	w.frameUnits = "RANGE"
+	w.setFrameRange(start, end...)
+	return w.parent
+}
+
+func (w *windowImpl) GROUPS(start FrameExtent, end ...FrameExtent) Window {
+	w.frameUnits = "GROUPS"
+	w.setFrameRange(start, end...)
+	return w.parent
+}
+
+func (w *windowImpl) setFrameRange(start FrameExtent, end ...FrameExtent) {
+	w.start = start
+	if len(end) > 0 {
+		w.end = end[0]
+	}
+}
+
+// PARTITION_BY window function constructor
+func PARTITION_BY(exp Expression, exprs ...Expression) Window {
+	funImpl := newWindowImpl(nil)
+	funImpl.partitionBy = append([]Expression{exp}, exprs...)
+	return funImpl
+}
+
+// ORDER_BY window function constructor
+func ORDER_BY(expr ...OrderByClause) Window {
+	funImpl := newWindowImpl(nil)
+	funImpl.orderBy.List = expr
+	return funImpl
+}
+
+// -----------------------------------------------
+
+// FrameExtent interface
+type FrameExtent interface {
+	Serializer
+	isFrameExtent()
+}
+
+// PRECEDING window frame clause
+func PRECEDING(offset Serializer) FrameExtent {
+	return &frameExtentImpl{
+		preceding: true,
+		offset:    offset,
+	}
+}
+
+// FOLLOWING window frame clause
+func FOLLOWING(offset Serializer) FrameExtent {
+	return &frameExtentImpl{
+		preceding: false,
+		offset:    offset,
+	}
+}
+
+type frameExtentImpl struct {
+	preceding bool
+	offset    Serializer
+}
+
+func (f *frameExtentImpl) isFrameExtent() {}
+
+func (f *frameExtentImpl) serialize(statement StatementType, out *SQLBuilder, options ...SerializeOption) {
+	if f == nil {
+		return
+	}
+	f.offset.serialize(statement, out, FallTrough(options)...)
+
+	if f.preceding {
+		out.WriteString("PRECEDING")
+	} else {
+		out.WriteString("FOLLOWING")
+	}
+}
+
+// -----------------------------------------------
+
+// Window function keywords
+var (
+	UNBOUNDED   = Keyword("UNBOUNDED")
+	CURRENT_ROW = frameExtentKeyword{"CURRENT ROW"}
+)
+
+type frameExtentKeyword struct {
+	Keyword
+}
+
+func (f frameExtentKeyword) isFrameExtent() {}
+
+// -----------------------------------------------
+
+// WindowName is used to specify window reference from WINDOW clause
+func WindowName(name string) Window {
+	newWindow := &windowName{name: name}
+	newWindow.parent = newWindow
+	return newWindow
+}
+
+type windowName struct {
+	windowImpl
+	name string
+}
+
+func (w windowName) serialize(statement StatementType, out *SQLBuilder, options ...SerializeOption) {
+	out.WriteByte('(')
+
+	out.WriteString(w.name)
+	w.windowImpl.serialize(statement, out, NoWrap.WithFallTrough(options)...)
+
+	out.WriteByte(')')
+}