Added test operator

pkg/yqlib/doc/String Operators.md

@@ -134,6 +134,24 @@ length: 3
 captures: []
 ```
 
+## Test using regex
+Like jq'q equivalant, this works like match but only returns true/false instead of full match details
+
+Given a sample.yml file of:
+```yaml
+- cat
+- dog
+```
+then
+```bash
+yq eval '.[] | test("at")' sample.yml
+```
+will output
+```yaml
+true
+false
+```
+
 ## Substitute / Replace string
 This uses golang regex, described [here](https://github.com/google/re2/wiki/Syntax)
 Note the use of `|=` to run in context of the current string value.

pkg/yqlib/expression_tokeniser.go

@@ -277,6 +277,7 @@ func initLexer() (*lex.Lexer, error) {
 	lexer.Add([]byte(`join`), opToken(joinStringOpType))
 	lexer.Add([]byte(`sub`), opToken(subStringOpType))
 	lexer.Add([]byte(`match`), opToken(matchOpType))
+	lexer.Add([]byte(`test`), opToken(testOpType))
 
 	lexer.Add([]byte(`any`), opToken(anyOpType))
 	lexer.Add([]byte(`any_c`), opToken(anyConditionOpType))

pkg/yqlib/lib.go

@@ -84,6 +84,7 @@ var sortKeysOpType = &operationType{Type: "SORT_KEYS", NumArgs: 1, Precedence: 5
 var joinStringOpType = &operationType{Type: "JOIN", NumArgs: 1, Precedence: 50, Handler: joinStringOperator}
 var subStringOpType = &operationType{Type: "SUBSTR", NumArgs: 1, Precedence: 50, Handler: substituteStringOperator}
 var matchOpType = &operationType{Type: "MATCH", NumArgs: 1, Precedence: 50, Handler: matchOperator}
+var testOpType = &operationType{Type: "MATCH", NumArgs: 1, Precedence: 50, Handler: testOperator}
 var splitStringOpType = &operationType{Type: "SPLIT", NumArgs: 1, Precedence: 50, Handler: splitStringOperator}
 
 var keysOpType = &operationType{Type: "KEYS", NumArgs: 0, Precedence: 50, Handler: keysOperator}

pkg/yqlib/operator_strings.go

@@ -112,6 +112,14 @@ func match(matchPrefs matchPreferences, regEx *regexp.Regexp, candidate *Candida
 		allIndices = [][]int{regEx.FindStringSubmatchIndex(value)}
 	}
 
+	log.Debug("allMatches, %v", allMatches)
+
+	// if all matches just has an empty array in it,
+	// then nothing matched
+	if len(allMatches) > 0 && len(allMatches[0]) == 0 {
+		return
+	}
+
 	for i, matches := range allMatches {
 		capturesNode := &yaml.Node{Kind: yaml.SequenceNode}
 		match, submatches := matches[0], matches[1:]
@@ -133,7 +141,7 @@ func match(matchPrefs matchPreferences, regEx *regexp.Regexp, candidate *Candida
 
 }
 
-func extractMatchArguments(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (string, matchPreferences, error) {
+func extractMatchArguments(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (*regexp.Regexp, matchPreferences, error) {
 	regExExpNode := expressionNode.Rhs
 
 	matchPrefs := matchPreferences{}
@@ -144,7 +152,7 @@ func extractMatchArguments(d *dataTreeNavigator, context Context, expressionNode
 		regExExpNode = block.Lhs
 		replacementNodes, err := d.GetMatchingNodes(context, block.Rhs)
 		if err != nil {
-			return "", matchPrefs, err
+			return nil, matchPrefs, err
 		}
 		paramText := ""
 		if replacementNodes.MatchingNodes.Front() != nil {
@@ -155,16 +163,16 @@ func extractMatchArguments(d *dataTreeNavigator, context Context, expressionNode
 			matchPrefs.Global = true
 		}
 		if strings.Contains(paramText, "i") {
-			return "", matchPrefs, fmt.Errorf(`'i' is not a valid option for match. To ignore case, use an expression like match("(?i)cat")`)
+			return nil, matchPrefs, fmt.Errorf(`'i' is not a valid option for match. To ignore case, use an expression like match("(?i)cat")`)
 		}
 		if len(paramText) > 0 {
-			return "", matchPrefs, fmt.Errorf(`Unrecognised match params '%v', please see docs at https://mikefarah.gitbook.io/yq/operators/string-operators`, paramText)
+			return nil, matchPrefs, fmt.Errorf(`Unrecognised match params '%v', please see docs at https://mikefarah.gitbook.io/yq/operators/string-operators`, paramText)
 		}
 	}
 
 	regExNodes, err := d.GetMatchingNodes(context.ReadOnlyClone(), regExExpNode)
 	if err != nil {
-		return "", matchPrefs, err
+		return nil, matchPrefs, err
 	}
 	log.Debug(NodesToString(regExNodes.MatchingNodes))
 	regExStr := ""
@@ -172,16 +180,12 @@ func extractMatchArguments(d *dataTreeNavigator, context Context, expressionNode
 		regExStr = regExNodes.MatchingNodes.Front().Value.(*CandidateNode).Node.Value
 	}
 	log.Debug("regEx %v", regExStr)
-	return regExStr, matchPrefs, nil
+	regEx, err := regexp.Compile(regExStr)
+	return regEx, matchPrefs, err
 }
 
 func matchOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
-	regExStr, matchPrefs, err := extractMatchArguments(d, context, expressionNode)
+	regEx, matchPrefs, err := extractMatchArguments(d, context, expressionNode)
-	if err != nil {
-		return Context{}, err
-	}
-
-	regEx, err := regexp.Compile(regExStr)
 	if err != nil {
 		return Context{}, err
 	}
@@ -201,6 +205,28 @@ func matchOperator(d *dataTreeNavigator, context Context, expressionNode *Expres
 	return context.ChildContext(results), nil
 }
 
+func testOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+	regEx, _, err := extractMatchArguments(d, context, expressionNode)
+	if err != nil {
+		return Context{}, err
+	}
+
+	var results = list.New()
+
+	for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
+		candidate := el.Value.(*CandidateNode)
+		node := unwrapDoc(candidate.Node)
+		if node.Tag != "!!str" {
+			return Context{}, fmt.Errorf("cannot match with %v, can only match strings. Hint: Most often you'll want to use '|=' over '=' for this operation", node.Tag)
+		}
+		matches := regEx.FindStringSubmatch(node.Value)
+		results.PushBack(createBooleanCandidate(candidate, len(matches) > 0))
+
+	}
+
+	return context.ChildContext(results), nil
+}
+
 func joinStringOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
 	log.Debugf("-- joinStringOperator")
 	joinStr := ""

pkg/yqlib/operator_strings_test.go

@@ -62,6 +62,35 @@ var stringsOperatorScenarios = []expressionScenario{
 			"D0, P[], ()::string: cat\noffset: 4\nlength: 3\ncaptures: []\n",
 		},
 	},
+	{
+		skipDoc:     true,
+		description: "No match",
+		document:    `dog`,
+		expression:  `match("cat"; "g")`,
+		expected:    []string{},
+	},
+	{
+		skipDoc:     true,
+		description: "No match",
+		expression:  `"dog" | match("cat", "g")`,
+		expected:    []string{},
+	},
+	{
+		skipDoc:     true,
+		description: "No match",
+		expression:  `"dog" | match("cat")`,
+		expected:    []string{},
+	},
+	{
+		description:    "Test using regex",
+		subdescription: "Like jq'q equivalant, this works like match but only returns true/false instead of full match details",
+		document:       `["cat", "dog"]`,
+		expression:     `.[] | test("at")`,
+		expected: []string{
+			"D0, P[0], (!!bool)::true\n",
+			"D0, P[1], (!!bool)::false\n",
+		},
+	},
 	{
 		description:    "Substitute / Replace string",
 		subdescription: "This uses golang regex, described [here](https://github.com/google/re2/wiki/Syntax)\nNote the use of `|=` to run in context of the current string value.",