sql/parser: Introduce IndirectionExpr and support for array subscripting

cockroachdb · Nov 16, 2016 · 504ec9e · 504ec9e
1 parent 6560bf4
commit 504ec9e
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Showing 10 changed files with 3,477 additions and 3,105 deletions.
diff --git a/pkg/sql/parser/eval.go b/pkg/sql/parser/eval.go
@@ -32,6 +32,7 @@ import (
 	"gopkg.in/inf.v0"
 
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
+	"github.com/cockroachdb/cockroach/pkg/util"
 	"github.com/cockroachdb/cockroach/pkg/util/decimal"
 	"github.com/cockroachdb/cockroach/pkg/util/duration"
 	"github.com/cockroachdb/cockroach/pkg/util/hlc"
@@ -1939,6 +1940,48 @@ func (expr *CastExpr) Eval(ctx *EvalContext) (Datum, error) {
 	return nil, fmt.Errorf("invalid cast: %s -> %s", d.ResolvedType(), expr.Type)
 }
 
+// Eval implements the TypedExpr interface.
+func (expr *IndirectionExpr) Eval(ctx *EvalContext) (Datum, error) {
+	var subscriptIdx int
+	for i, part := range expr.Indirection {
+		switch t := part.(type) {
+		case *ArraySubscript:
+			if t.Slice {
+				return nil, util.UnimplementedWithIssueErrorf(2115, "ARRAY slicing in %s", expr)
+			}
+			if i > 0 {
+				return nil, util.UnimplementedWithIssueErrorf(2115, "multidimensional ARRAY %s", expr)
+			}
+
+			d, err := t.Begin.(TypedExpr).Eval(ctx)
+			if err != nil {
+				return nil, err
+			}
+			if d == DNull {
+				return d, nil
+			}
+			subscriptIdx = int(*d.(*DInt))
+		default:
+			return nil, errors.Errorf("syntax not yet supported: %s", expr.Indirection)
+		}
+	}
+
+	d, err := expr.Expr.(TypedExpr).Eval(ctx)
+	if err != nil {
+		return nil, err
+	}
+	if d == DNull {
+		return d, nil
+	}
+
+	// Index into the DArray, using 1-indexing.
+	arr := d.(*DArray)
+	if subscriptIdx < 1 || subscriptIdx > len(*arr) {
+		return DNull, nil
+	}
+	return (*arr)[subscriptIdx-1], nil
+}
+
 // Eval implements the TypedExpr interface.
 func (expr *AnnotateTypeExpr) Eval(ctx *EvalContext) (Datum, error) {
 	return expr.Expr.(TypedExpr).Eval(ctx)

diff --git a/pkg/sql/parser/expr.go b/pkg/sql/parser/expr.go
@@ -1002,6 +1002,20 @@ func (node *CastExpr) castTypeAndValidArgTypes() (Type, []Type) {
 	return colTypeToTypeAndValidArgTypes(node.Type)
 }
 
+// IndirectionExpr represents a subscript expression.
+type IndirectionExpr struct {
+	Expr        Expr
+	Indirection UnresolvedName
+
+	typeAnnotation
+}
+
+// Format implements the NodeFormatter interface.
+func (node *IndirectionExpr) Format(buf *bytes.Buffer, f FmtFlags) {
+	FormatNode(buf, f, node.Expr)
+	FormatNode(buf, f, node.Indirection)
+}
+
 type annotateSyntaxMode int
 
 const (
@@ -1088,6 +1102,7 @@ func (node Exprs) String() string             { return AsString(node) }
 func (node *FuncExpr) String() string         { return AsString(node) }
 func (node *IfExpr) String() string           { return AsString(node) }
 func (node *IndexedVar) String() string       { return AsString(node) }
+func (node *IndirectionExpr) String() string  { return AsString(node) }
 func (node *IsOfTypeExpr) String() string     { return AsString(node) }
 func (node Name) String() string              { return AsString(node) }
 func (node *NotExpr) String() string          { return AsString(node) }

diff --git a/pkg/sql/parser/parse_test.go b/pkg/sql/parser/parse_test.go
@@ -298,8 +298,11 @@ func TestParse(t *testing.T) {
 		{`SELECT true AND NULL`},
 		{`SELECT true = false`},
 		{`SELECT (true = false)`},
+		{`SELECT (ARRAY['a', 'b'])[2]`},
 		{`SELECT (SELECT 1)`},
 		{`SELECT ((SELECT 1))`},
+		{`SELECT (SELECT ARRAY['a', 'b'])[2]`},
+		{`SELECT ((SELECT ARRAY['a', 'b']))[2]`},
 		{`SELECT ((((VALUES (1)))))`},
 		{`SELECT EXISTS (SELECT 1)`},
 		{`SELECT (VALUES (1))`},