Draft of DESC for query planner

Simple planing explanation of the provided query.

Author: xllora

bql/planner/planner.go

@@ -230,19 +230,10 @@ func newQueryPlan(ctx context.Context, store storage.Store, stm *semantic.Statem
 	if err != nil {
 		return nil, err
 	}
-	var gs []storage.Graph
-	for _, g := range stm.Graphs() {
-		ng, err := store.Graph(ctx, g)
-		if err != nil {
-			return nil, err
-		}
-		gs = append(gs, ng)
-	}
 	return &queryPlan{
 		stm:       stm,
 		store:     store,
 		bndgs:     bs,
-		grfs:      gs,
 		grfsNames: stm.Graphs(),
 		cls:       stm.SortedGraphPatternClauses(),
 		tbl:       t,
@@ -634,6 +625,14 @@ func (p *queryPlan) limit() {
 
 // Execute queries the indicated graphs.
 func (p *queryPlan) Execute(ctx context.Context) (*table.Table, error) {
+	// Collect the graph references.
+	for _, g := range p.stm.Graphs() {
+		ng, err := p.store.Graph(ctx, g)
+		if err != nil {
+			return nil, err
+		}
+		p.grfs = append(p.grfs, ng)
+	}
 	// Retrieve the data.
 	lo := p.stm.GlobalLookupOptions()
 	if err := p.processGraphPattern(ctx, lo); err != nil {

bql/semantic/semantic.go

@@ -122,7 +122,161 @@ type GraphClause struct {
 
 // String returns a readable representaion of a graph clause.
 func (c *GraphClause) String() string {
-	return "not implemented"
+	b := bytes.NewBufferString("{ ")
+
+	// Subject section.
+	if c.S != nil {
+		b.WriteString(c.S.String())
+	} else {
+		b.WriteString(c.SBinding)
+	}
+	if c.SAlias != "" {
+		b.WriteString(" AS ")
+		b.WriteString(c.SAlias)
+	}
+	if c.STypeAlias != "" {
+		b.WriteString(" TYPE ")
+		b.WriteString(c.STypeAlias)
+	}
+	if c.SIDAlias != "" {
+		b.WriteString(" ID ")
+		b.WriteString(c.SIDAlias)
+	}
+
+	// Predicate section.
+	predicate := false
+	if c.P != nil {
+		b.WriteString(" ")
+		b.WriteString(c.P.String())
+		predicate = true
+	}
+	if c.PBinding != "" {
+		b.WriteString(" ")
+		b.WriteString(c.PBinding)
+	}
+	if c.PID != "" {
+		b.WriteString(" \"")
+		b.WriteString(c.PID)
+		b.WriteString("\"")
+	}
+	if !predicate {
+		if !c.PTemporal {
+			b.WriteString("@[]")
+		} else {
+			b.WriteString("@[")
+			if c.PAnchorBinding != "" {
+				b.WriteString(c.PAnchorBinding)
+				if c.PAnchorAlias != "" {
+					b.WriteString(" at ")
+					b.WriteString(c.PAnchorAlias)
+				}
+			} else {
+				if c.PLowerBound != nil {
+					b.WriteString(c.PLowerBound.String())
+				} else {
+					if c.PLowerBoundAlias != "" {
+						b.WriteString(c.PLowerBoundAlias)
+					}
+				}
+				b.WriteString(",")
+				if c.PUpperBound != nil {
+					b.WriteString(c.PUpperBound.String())
+				} else {
+					if c.PUpperBoundAlias != "" {
+						b.WriteString(c.PUpperBoundAlias)
+					}
+				}
+			}
+			b.WriteString("]")
+		}
+	}
+
+	if c.PAlias != "" {
+		b.WriteString(" AS ")
+		b.WriteString(c.PAlias)
+	}
+	if c.PIDAlias != "" {
+		b.WriteString(" ID ")
+		b.WriteString(c.PIDAlias)
+	}
+
+	// Object section.
+	// Node portion.
+	object := false
+	if c.O != nil {
+		b.WriteString(" ")
+		b.WriteString(c.O.String())
+		object = true
+	} else {
+		b.WriteString(" ")
+		b.WriteString(c.OBinding)
+		object = true
+	}
+	if c.OAlias != "" {
+		b.WriteString(" AS ")
+		b.WriteString(c.OAlias)
+	}
+	if c.OTypeAlias != "" {
+		b.WriteString(" TYPE ")
+		b.WriteString(c.OTypeAlias)
+	}
+	if c.OIDAlias != "" {
+		b.WriteString(" ID ")
+		b.WriteString(c.OIDAlias)
+	}
+	// Predicate portion.
+	if !object {
+		if c.OBinding != "" {
+			b.WriteString(" ")
+			b.WriteString(c.OBinding)
+		}
+		if c.OID != "" {
+			b.WriteString(" \"")
+			b.WriteString(c.OID)
+			b.WriteString("\"")
+		}
+		if !c.OTemporal {
+			b.WriteString("[]")
+		} else {
+			b.WriteString("[")
+			if c.OAnchorBinding != "" {
+				b.WriteString(c.OAnchorBinding)
+				if c.OAnchorAlias != "" {
+					b.WriteString(" at ")
+					b.WriteString(c.OAnchorAlias)
+				}
+			} else {
+				if c.OLowerBound != nil {
+					b.WriteString(c.OLowerBound.String())
+				} else {
+					if c.OLowerBoundAlias != "" {
+						b.WriteString(c.OLowerBoundAlias)
+					}
+				}
+				b.WriteString(",")
+				if c.OUpperBound != nil {
+					b.WriteString(c.OUpperBound.String())
+				} else {
+					if c.OUpperBoundAlias != "" {
+						b.WriteString(c.OUpperBoundAlias)
+					}
+				}
+			}
+			b.WriteString("]")
+		}
+	}
+
+	if c.OAlias != "" {
+		b.WriteString(" AS ")
+		b.WriteString(c.OAlias)
+	}
+	if c.OIDAlias != "" {
+		b.WriteString(" ID ")
+		b.WriteString(c.OIDAlias)
+	}
+
+	b.WriteString(" }")
+	return b.String()
 }
 
 // Specificity return