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121 lines
2.9 KiB
Go
121 lines
2.9 KiB
Go
package ast
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import (
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"strconv"
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"github.com/neilotoole/sq/libsq/ast/internal/slq"
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)
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// RowRangeNode models a range, effectively {OFFSET,LIMIT}.
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type RowRangeNode struct {
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baseNode
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Offset int
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Limit int
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}
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func newRowRangeNode(ctx *slq.RowRangeContext, offset, limit int) *RowRangeNode {
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rr := &RowRangeNode{}
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rr.ctx = ctx
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rr.text = ctx.GetText()
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rr.Offset = offset
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rr.Limit = limit
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return rr
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}
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// String implements ast.Node.
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func (rr *RowRangeNode) String() string {
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return rr.Text()
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}
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// Range returns the offset and limit.
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func (rr *RowRangeNode) Range() (offset, limit int) {
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offset = rr.Offset
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limit = rr.Limit
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return offset, limit
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}
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// SetParent implements ast.Node.
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func (rr *RowRangeNode) SetParent(parent Node) error {
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seg, ok := parent.(*SegmentNode)
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if !ok {
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return errorf("%T requires parent of type *%s", rr, typeSegmentNode)
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}
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rr.parent = seg
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return nil
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}
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// VisitRowRange implements slq.SLQVisitor.
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func (v *parseTreeVisitor) VisitRowRange(ctx *slq.RowRangeContext) any {
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// [] select all rows (no range)
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// [1] select row[1]
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// [10:15] select rows 10 thru 15
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// [0:15] select rows 0 thru 15
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// [:15] same as above (0 thru 15)
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// [10:] select all rows from 10 onwards
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if ctx.COLON() == nil && len(ctx.AllNN()) == 0 {
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// [] select all rows, aka no range
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return nil
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}
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if ctx.COLON() == nil {
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// [1] -- select row[1]
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if len(ctx.AllNN()) != 1 {
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return errorf("row range: expected one integer but got %d", len(ctx.AllNN()))
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}
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i, _ := strconv.Atoi(ctx.AllNN()[0].GetText())
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rr := newRowRangeNode(ctx, i, 1)
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return v.cur.AddChild(rr)
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}
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// there's a colon... can only be one or two ints
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if len(ctx.AllNN()) > 2 {
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return errorf("row range: expected one or two integers but got %d", len(ctx.AllNN()))
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}
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if len(ctx.AllNN()) == 2 {
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// [10:15] -- select rows 10 thru 15
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offset, _ := strconv.Atoi(ctx.AllNN()[0].GetText())
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finish, _ := strconv.Atoi(ctx.AllNN()[1].GetText())
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limit := finish - offset
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rr := newRowRangeNode(ctx, offset, limit)
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return v.cur.AddChild(rr)
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}
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// it's one of these two cases:
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// [:15] (0 thru 15)
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// [10:] select all rows from 10 onwards
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// so we need to determine if the INT is before or after the colon
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var offset int
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limit := -1
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if ctx.COLON().GetSymbol().GetTokenIndex() < ctx.AllNN()[0].GetSymbol().GetTokenIndex() {
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// [:15] (0 thru 15)
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offset = 0
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limit, _ = strconv.Atoi(ctx.AllNN()[0].GetText())
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} else {
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// [10:] select all rows from 10 onwards
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offset, _ = strconv.Atoi(ctx.AllNN()[0].GetText())
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}
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rr := newRowRangeNode(ctx, offset, limit)
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return v.cur.AddChild(rr)
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}
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// verifyRowRange validates the RowRangeNode element.
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func verifyRowRange(w *Walker, node Node) error {
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rr, ok := node.(*RowRangeNode)
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if !ok {
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return errorf("expected %s but got %T", typeRowRangeNode, node)
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}
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if w.state != nil {
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return errorf("only one row range element permitted")
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}
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w.state = rr
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// TODO: check that the row range is after a selectable
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return nil
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}
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