add Conditions function

Refs https://github.com/tendermint/tendermint/pull/835

pubsub/query/query.go

@@ -22,6 +22,14 @@ type Query struct {
 	parser *QueryParser
 }
 
+// Condition represents a single condition within a query and consists of tag
+// (e.g. "tx.gas"), operator (e.g. "=") and operand (e.g. "7").
+type Condition struct {
+	Tag     string
+	Op      Operator
+	Operand interface{}
+}
+
 // New parses the given string and returns a query or error if the string is
 // invalid.
 func New(s string) (*Query, error) {
@@ -48,17 +56,91 @@ func (q *Query) String() string {
 	return q.str
 }
 
-type operator uint8
+// Operator is an operator that defines some kind of relation between tag and
+// operand (equality, etc.).
+type Operator uint8
 
 const (
-	opLessEqual operator = iota
+	// "<="
-	opGreaterEqual
+	OpLessEqual Operator = iota
-	opLess
+	// ">="
-	opGreater
+	OpGreaterEqual
-	opEqual
+	// "<"
-	opContains
+	OpLess
+	// ">"
+	OpGreater
+	// "="
+	OpEqual
+	// "CONTAINS"; used to check if a string contains a certain sub string.
+	OpContains
 )
 
+// Conditions returns a list of conditions.
+func (q *Query) Conditions() []Condition {
+	conditions := make([]Condition, 0)
+
+	buffer, begin, end := q.parser.Buffer, 0, 0
+
+	var tag string
+	var op Operator
+
+	// tokens must be in the following order: tag ("tx.gas") -> operator ("=") -> operand ("7")
+	for _, token := range q.parser.Tokens() {
+		switch token.pegRule {
+
+		case rulePegText:
+			begin, end = int(token.begin), int(token.end)
+		case ruletag:
+			tag = buffer[begin:end]
+		case rulele:
+			op = OpLessEqual
+		case rulege:
+			op = OpGreaterEqual
+		case rulel:
+			op = OpLess
+		case ruleg:
+			op = OpGreater
+		case ruleequal:
+			op = OpEqual
+		case rulecontains:
+			op = OpContains
+		case rulevalue:
+			// strip single quotes from value (i.e. "'NewBlock'" -> "NewBlock")
+			valueWithoutSingleQuotes := buffer[begin+1 : end-1]
+			conditions = append(conditions, Condition{tag, op, valueWithoutSingleQuotes})
+		case rulenumber:
+			number := buffer[begin:end]
+			if strings.Contains(number, ".") { // if it looks like a floating-point number
+				value, err := strconv.ParseFloat(number, 64)
+				if err != nil {
+					panic(fmt.Sprintf("got %v while trying to parse %s as float64 (should never happen if the grammar is correct)", err, number))
+				}
+				conditions = append(conditions, Condition{tag, op, value})
+			} else {
+				value, err := strconv.ParseInt(number, 10, 64)
+				if err != nil {
+					panic(fmt.Sprintf("got %v while trying to parse %s as int64 (should never happen if the grammar is correct)", err, number))
+				}
+				conditions = append(conditions, Condition{tag, op, value})
+			}
+		case ruletime:
+			value, err := time.Parse(time.RFC3339, buffer[begin:end])
+			if err != nil {
+				panic(fmt.Sprintf("got %v while trying to parse %s as time.Time / RFC3339 (should never happen if the grammar is correct)", err, buffer[begin:end]))
+			}
+			conditions = append(conditions, Condition{tag, op, value})
+		case ruledate:
+			value, err := time.Parse("2006-01-02", buffer[begin:end])
+			if err != nil {
+				panic(fmt.Sprintf("got %v while trying to parse %s as time.Time / '2006-01-02' (should never happen if the grammar is correct)", err, buffer[begin:end]))
+			}
+			conditions = append(conditions, Condition{tag, op, value})
+		}
+	}
+
+	return conditions
+}
+
 // Matches returns true if the query matches the given set of tags, false otherwise.
 //
 // For example, query "name=John" matches tags = {"name": "John"}. More
@@ -71,7 +153,7 @@ func (q *Query) Matches(tags map[string]interface{}) bool {
 	buffer, begin, end := q.parser.Buffer, 0, 0
 
 	var tag string
-	var op operator
+	var op Operator
 
 	// tokens must be in the following order: tag ("tx.gas") -> operator ("=") -> operand ("7")
 	for _, token := range q.parser.Tokens() {
@@ -82,17 +164,17 @@ func (q *Query) Matches(tags map[string]interface{}) bool {
 		case ruletag:
 			tag = buffer[begin:end]
 		case rulele:
-			op = opLessEqual
+			op = OpLessEqual
 		case rulege:
-			op = opGreaterEqual
+			op = OpGreaterEqual
 		case rulel:
-			op = opLess
+			op = OpLess
 		case ruleg:
-			op = opGreater
+			op = OpGreater
 		case ruleequal:
-			op = opEqual
+			op = OpEqual
 		case rulecontains:
-			op = opContains
+			op = OpContains
 		case rulevalue:
 			// strip single quotes from value (i.e. "'NewBlock'" -> "NewBlock")
 			valueWithoutSingleQuotes := buffer[begin+1 : end-1]
@@ -149,7 +231,7 @@ func (q *Query) Matches(tags map[string]interface{}) bool {
 // value from it to the operand using the operator.
 //
 // "tx.gas", "=", "7", { "tx.gas": 7, "tx.ID": "4AE393495334" }
-func match(tag string, op operator, operand reflect.Value, tags map[string]interface{}) bool {
+func match(tag string, op Operator, operand reflect.Value, tags map[string]interface{}) bool {
 	// look up the tag from the query in tags
 	value, ok := tags[tag]
 	if !ok {
@@ -163,15 +245,15 @@ func match(tag string, op operator, operand reflect.Value, tags map[string]inter
 			return false
 		}
 		switch op {
-		case opLessEqual:
+		case OpLessEqual:
 			return v.Before(operandAsTime) || v.Equal(operandAsTime)
-		case opGreaterEqual:
+		case OpGreaterEqual:
 			return v.Equal(operandAsTime) || v.After(operandAsTime)
-		case opLess:
+		case OpLess:
 			return v.Before(operandAsTime)
-		case opGreater:
+		case OpGreater:
 			return v.After(operandAsTime)
-		case opEqual:
+		case OpEqual:
 			return v.Equal(operandAsTime)
 		}
 	case reflect.Float64:
@@ -197,15 +279,15 @@ func match(tag string, op operator, operand reflect.Value, tags map[string]inter
 			panic(fmt.Sprintf("Incomparable types: %T (%v) vs float64 (%v)", value, value, operandFloat64))
 		}
 		switch op {
-		case opLessEqual:
+		case OpLessEqual:
 			return v <= operandFloat64
-		case opGreaterEqual:
+		case OpGreaterEqual:
 			return v >= operandFloat64
-		case opLess:
+		case OpLess:
 			return v < operandFloat64
-		case opGreater:
+		case OpGreater:
 			return v > operandFloat64
-		case opEqual:
+		case OpEqual:
 			return v == operandFloat64
 		}
 	case reflect.Int64:
@@ -231,15 +313,15 @@ func match(tag string, op operator, operand reflect.Value, tags map[string]inter
 			panic(fmt.Sprintf("Incomparable types: %T (%v) vs int64 (%v)", value, value, operandInt))
 		}
 		switch op {
-		case opLessEqual:
+		case OpLessEqual:
 			return v <= operandInt
-		case opGreaterEqual:
+		case OpGreaterEqual:
 			return v >= operandInt
-		case opLess:
+		case OpLess:
 			return v < operandInt
-		case opGreater:
+		case OpGreater:
 			return v > operandInt
-		case opEqual:
+		case OpEqual:
 			return v == operandInt
 		}
 	case reflect.String:
@@ -248,9 +330,9 @@ func match(tag string, op operator, operand reflect.Value, tags map[string]inter
 			return false
 		}
 		switch op {
-		case opEqual:
+		case OpEqual:
 			return v == operand.String()
-		case opContains:
+		case OpContains:
 			return strings.Contains(v, operand.String())
 		}
 	default:

pubsub/query/query_test.go

@@ -62,3 +62,24 @@ func TestMustParse(t *testing.T) {
 	assert.Panics(t, func() { query.MustParse("=") })
 	assert.NotPanics(t, func() { query.MustParse("tm.events.type='NewBlock'") })
 }
+
+func TestConditions(t *testing.T) {
+	txTime, err := time.Parse(time.RFC3339, "2013-05-03T14:45:00Z")
+	require.NoError(t, err)
+
+	testCases := []struct {
+		s          string
+		conditions []query.Condition
+	}{
+		{"tm.events.type='NewBlock'", []query.Condition{query.Condition{"tm.events.type", query.OpEqual, "NewBlock"}}},
+		{"tx.gas > 7 AND tx.gas < 9", []query.Condition{query.Condition{"tx.gas", query.OpGreater, int64(7)}, query.Condition{"tx.gas", query.OpLess, int64(9)}}},
+		{"tx.time >= TIME 2013-05-03T14:45:00Z", []query.Condition{query.Condition{"tx.time", query.OpGreaterEqual, txTime}}},
+	}
+
+	for _, tc := range testCases {
+		query, err := query.New(tc.s)
+		require.Nil(t, err)
+
+		assert.Equal(t, tc.conditions, query.Conditions())
+	}
+}