Add 'like' functionality in where clause (#64)

lexical/lexemes.go

@@ -11,3 +11,4 @@ const L_LIMIT = "limit"
 const L_IN = "in"
 const L_ASC = "asc"
 const L_DESC = "desc"
+const L_LIKE = "like"

lexical/lexical.go

@@ -218,7 +218,8 @@ func lexemeToToken(lexeme string) uint8 {
 		return T_ASC
 	case L_DESC:
 		return T_DESC
-
+	case L_LIKE:
+		return T_LIKE
 	}
 	return T_ID
 }

lexical/tokens.go

@@ -25,6 +25,7 @@ const T_PARENTH_L = 22
 const T_PARENTH_R = 23
 const T_IN = 24
 const T_ASC = 25
+const T_LIKE = 26
 const T_EOF = 0
 const T_FUCK = 66
 

parser/ast.go

@@ -1,6 +1,7 @@
 package parser
 
 import (
+	"regexp"
 	"strconv"
 	"strings"
 	"time"
@@ -68,6 +69,12 @@ type NodeNotEqual struct {
 	rightValue NodeExpr
 }
 
+type NodeLike struct {
+	leftValue  NodeExpr
+	rightValue NodeExpr
+	Pattern    *regexp.Regexp
+}
+
 type NodeGreater struct {
 	leftValue  NodeExpr
 	rightValue NodeExpr
@@ -201,6 +208,31 @@ func (n *NodeNotEqual) LeftValue() NodeExpr {
 	return n.leftValue
 }
 
+// LIKE
+func (n *NodeLike) Assertion(lvalue string, rvalue string) bool {
+	return n.Pattern.MatchString(lvalue)
+}
+
+func (n *NodeLike) Operator() uint8 {
+	return lexical.T_LIKE
+}
+
+func (n *NodeLike) SetLeftValue(e NodeExpr) {
+	n.leftValue = e
+}
+
+func (n *NodeLike) SetRightValue(e NodeExpr) {
+	n.rightValue = e
+}
+
+func (n *NodeLike) RightValue() NodeExpr {
+	return n.rightValue
+}
+
+func (n *NodeLike) LeftValue() NodeExpr {
+	return n.leftValue
+}
+
 // GREATER
 func (n *NodeGreater) Assertion(lvalue string, rvalue string) bool {
 	time := ExtractDate(rvalue)

parser/parser.go

@@ -2,7 +2,9 @@ package parser
 
 import (
 	"fmt"
+	"regexp"
 	"strconv"
+	"strings"
 	_ "unicode"
 
 	"github.com/cloudson/gitql/lexical"
@@ -339,7 +341,7 @@ func gWC3(eating bool) (NodeExpr, error) {
 	return expr, nil
 }
 
-// where cond 'equal', 'in' and 'not equal'
+// where cond 'equal', 'in', 'like' and 'not equal'
 func gWC4(eating bool) (NodeExpr, error) {
 	if eating {
 		token, err := lexical.Token()
@@ -373,6 +375,19 @@ func gWC4(eating bool) (NodeExpr, error) {
 		}
 		op.SetRightValue(expr2)
 		return op, nil
+	case lexical.T_LIKE:
+		op := new(NodeLike)
+		op.SetLeftValue(expr)
+		expr2, err2 := gWC4(true)
+		if err2 != nil {
+			return nil, err2
+		}
+		op.SetRightValue(expr2)
+		// Compile the regex while parsing, so that
+		// we don't need to compile for every row
+		rx := strings.Replace(expr2.(*NodeLiteral).Value(), "%", "(.*)", -1)
+		op.Pattern, err2 = regexp.Compile(rx)
+		return op, err2
 	case lexical.T_IN:
 		op := new(NodeIn)
 		op.SetLeftValue(expr)

runtime/commits_test.go

@@ -84,6 +84,14 @@ func TestSelectedFieldsCount(t *testing.T) {
 	}
 }
 
+func TestWhereLike(t *testing.T) {
+	query := "select hash, author from commits where hash like '%8813f1c5e6f5d10ef%'"
+	table := getTableForQuery(query, "../", t)
+	if len(table.rows) != 1 {
+		t.Errorf("Expecting 1 row. Got %d rows", len(table.rows))
+  }
+}
+
 func TestNotEqualsInWhereLTGT(t *testing.T) {
 	queryData := "select committer, hash from commits limit 1"
 	table := getTableForQuery(queryData, "../", t)
@@ -94,6 +102,7 @@ func TestNotEqualsInWhereLTGT(t *testing.T) {
 		t.Errorf("Still got the same committer as the first one. - %s", firstCommitter)
 	}
 }
+
 func TestNotEqualsInWhere(t *testing.T) {
 	queryData := "select committer, hash from commits limit 1"
 	table := getTableForQuery(queryData, "../", t)

runtime/visitor.go

@@ -117,11 +117,13 @@ func (v *RuntimeVisitor) VisitExpr(n parser.NodeExpr) error {
 	case reflect.TypeOf(new(parser.NodeIn)):
 		g := n.(*parser.NodeIn)
 		return v.VisitIn(g)
+	case reflect.TypeOf(new(parser.NodeLike)):
+		g := n.(*parser.NodeLike)
+		return v.VisitLike(g)
 	case reflect.TypeOf(new(parser.NodeNotEqual)):
 		g := n.(*parser.NodeNotEqual)
 		return v.VisitNotEqual(g)
 	}
-
 	return nil
 }
 
@@ -132,6 +134,13 @@ func (v *RuntimeVisitor) VisitEqual(n *parser.NodeEqual) error {
 	return nil
 }
 
+func (v *RuntimeVisitor) VisitLike(n *parser.NodeLike) error {
+  lvalue := n.LeftValue().(*parser.NodeId).Value()
+	rvalue := n.RightValue().(*parser.NodeLiteral).Value()
+	boolRegister = n.Assertion(metadata(lvalue), rvalue)
+	return nil
+}
+
 func (v *RuntimeVisitor) VisitNotEqual(n *parser.NodeNotEqual) error {
 	lvalue := n.LeftValue().(*parser.NodeId).Value()
 	rvalue := n.RightValue().(*parser.NodeLiteral).Value()
@@ -143,19 +152,15 @@ func (v *RuntimeVisitor) VisitGreater(n *parser.NodeGreater) error {
 	lvalue := n.LeftValue().(*parser.NodeId).Value()
 	lvalue = metadata(lvalue)
 	rvalue := n.RightValue().(*parser.NodeLiteral).Value()
-
 	boolRegister = n.Assertion(lvalue, rvalue)
-
 	return nil
 }
 
 func (v *RuntimeVisitor) VisitSmaller(n *parser.NodeSmaller) error {
 	lvalue := n.LeftValue().(*parser.NodeId).Value()
 	lvalue = metadata(lvalue)
 	rvalue := n.RightValue().(*parser.NodeLiteral).Value()
-
 	boolRegister = n.Assertion(lvalue, rvalue)
-
 	return nil
 }
 
@@ -164,7 +169,6 @@ func (v *RuntimeVisitor) VisitOr(n *parser.NodeOr) error {
 	boolLeft := boolRegister
 	v.VisitExpr(n.RightValue())
 	boolRight := boolRegister
-
 	boolRegister = boolLeft || boolRight
 	return nil
 }