feat: loop over a matrix (#1767)

task_test.go

@@ -2374,6 +2374,10 @@ func TestForCmds(t *testing.T) {
 			name:           "loop-explicit",
 			expectedOutput: "a\nb\nc\n",
 		},
+		{
+			name:           "loop-matrix",
+			expectedOutput: "windows/amd64\nwindows/arm64\nlinux/amd64\nlinux/arm64\ndarwin/amd64\ndarwin/arm64\n",
+		},
 		{
 			name:           "loop-sources",
 			expectedOutput: "bar\nfoo\n",
@@ -2431,6 +2435,17 @@ func TestForDeps(t *testing.T) {
 			name:                   "loop-explicit",
 			expectedOutputContains: []string{"a\n", "b\n", "c\n"},
 		},
+		{
+			name: "loop-matrix",
+			expectedOutputContains: []string{
+				"windows/amd64\n",
+				"windows/arm64\n",
+				"linux/amd64\n",
+				"linux/arm64\n",
+				"darwin/amd64\n",
+				"darwin/arm64\n",
+			},
+		},
 		{
 			name:                   "loop-sources",
 			expectedOutputContains: []string{"bar\n", "foo\n"},

taskfile/ast/for.go

@@ -8,11 +8,12 @@ import (
 )
 
 type For struct {
-	From  string
-	List  []any
-	Var   string
-	Split string
-	As    string
+	From   string
+	List   []any
+	Matrix map[string][]any
+	Var    string
+	Split  string
+	As     string
 }
 
 func (f *For) UnmarshalYAML(node *yaml.Node) error {
@@ -36,16 +37,21 @@ func (f *For) UnmarshalYAML(node *yaml.Node) error {
 
 	case yaml.MappingNode:
 		var forStruct struct {
-			Var   string
-			Split string
-			As    string
+			Matrix map[string][]any
+			Var    string
+			Split  string
+			As     string
 		}
 		if err := node.Decode(&forStruct); err != nil {
 			return errors.NewTaskfileDecodeError(err, node)
 		}
-		if forStruct.Var == "" {
+		if forStruct.Var == "" && forStruct.Matrix == nil {
 			return errors.NewTaskfileDecodeError(nil, node).WithMessage("invalid keys in for")
 		}
+		if forStruct.Var != "" && forStruct.Matrix != nil {
+			return errors.NewTaskfileDecodeError(nil, node).WithMessage("cannot use both var and matrix in for")
+		}
+		f.Matrix = forStruct.Matrix
 		f.Var = forStruct.Var
 		f.Split = forStruct.Split
 		f.As = forStruct.As
@@ -60,10 +66,11 @@ func (f *For) DeepCopy() *For {
 		return nil
 	}
 	return &For{
-		From:  f.From,
-		List:  deepcopy.Slice(f.List),
-		Var:   f.Var,
-		Split: f.Split,
-		As:    f.As,
+		From:   f.From,
+		List:   deepcopy.Slice(f.List),
+		Matrix: deepcopy.Map(f.Matrix),
+		Var:    f.Var,
+		Split:  f.Split,
+		As:     f.As,
 	}
 }

testdata/for/cmds/Taskfile.yml

@@ -7,6 +7,14 @@ tasks:
       - for: ["a", "b", "c"]
         cmd: echo "{{.ITEM}}"
 
+  loop-matrix:
+    cmds:
+      - for:
+          matrix:
+            OS: ["windows", "linux", "darwin"]
+            ARCH: ["amd64", "arm64"]
+        cmd: echo "{{.ITEM.OS}}/{{.ITEM.ARCH}}"
+
   # Loop over the task's sources
   loop-sources:
     sources:

testdata/for/deps/Taskfile.yml

@@ -9,6 +9,16 @@ tasks:
         vars:
           TEXT: "{{.ITEM}}"
 
+  loop-matrix:
+    deps:
+      - for:
+          matrix:
+            OS: ["windows", "linux", "darwin"]
+            ARCH: ["amd64", "arm64"]
+        task: echo
+        vars:
+          TEXT: "{{.ITEM.OS}}/{{.ITEM.ARCH}}"
+
   # Loop over the task's sources
   loop-sources:
     sources:

variables.go

@@ -271,9 +271,13 @@ func itemsFromFor(
 ) ([]any, []string, error) {
 	var keys []string // The list of keys to loop over (only if looping over a map)
 	var values []any  // The list of values to loop over
+	// Get the list from a matrix
+	if f.Matrix != nil {
+		return asAnySlice(product(f.Matrix)), nil, nil
+	}
 	// Get the list from the explicit for list
 	if len(f.List) > 0 {
-		values = f.List
+		return f.List, nil, nil
 	}
 	// Get the list from the task sources
 	if f.From == "sources" {
@@ -322,3 +326,46 @@ func itemsFromFor(
 	}
 	return values, keys, nil
 }
+
+// product generates the cartesian product of the input map of slices.
+func product(inputMap map[string][]any) []map[string]any {
+	if len(inputMap) == 0 {
+		return nil
+	}
+
+	// Extract the keys and corresponding slices
+	keys := make([]string, 0, len(inputMap))
+	slices := make([][]any, 0, len(inputMap))
+	for key, slice := range inputMap {
+		keys = append(keys, key)
+		slices = append(slices, slice)
+	}
+
+	// Start with an empty product result
+	result := []map[string]any{{}}
+
+	// Iterate over each slice in the slices
+	for i, slice := range slices {
+		var newResult []map[string]any
+
+		// For each combination in the current result
+		for _, combination := range result {
+			// Append each element from the current slice to the combinations
+			for _, item := range slice {
+				newComb := make(map[string]any, len(combination))
+				// Copy the existing combination
+				for k, v := range combination {
+					newComb[k] = v
+				}
+				// Add the current item with the corresponding key
+				newComb[keys[i]] = item
+				newResult = append(newResult, newComb)
+			}
+		}
+
+		// Update result with the new combinations
+		result = newResult
+	}
+
+	return result
+}

website/docs/usage.mdx

@@ -1297,9 +1297,9 @@ tasks:
 
 ## Looping over values
 
-As of v3.28.0, Task allows you to loop over certain values and execute a command
-for each. There are a number of ways to do this depending on the type of value
-you want to loop over.
+Task allows you to loop over certain values and execute a command for each.
+There are a number of ways to do this depending on the type of value you want to
+loop over.
 
 ### Looping over a static list
 
@@ -1316,6 +1316,37 @@ tasks:
         cmd: cat {{ .ITEM }}
 ```
 
+### Looping over a matrix
+
+If you need to loop over all permutations of multiple lists, you can use the
+`matrix` property. This should be familiar to anyone who has used a matrix in a
+CI/CD pipeline.
+
+```yaml
+version: '3'
+
+tasks:
+  default:
+    silent: true
+    cmds:
+      - for:
+          matrix:
+            OS: ["windows", "linux", "darwin"]
+            ARCH: ["amd64", "arm64"]
+        cmd: echo "{{.ITEM.OS}}/{{.ITEM.ARCH}}"
+```
+
+This will output:
+
+```txt
+windows/amd64
+windows/arm64
+linux/amd64
+linux/arm64
+darwin/amd64
+darwin/arm64
+```
+
 ### Looping over your task's sources
 
 You are also able to loop over the sources of your task:

website/static/schema.json

@@ -431,6 +431,9 @@
         },
         {
           "$ref": "#/definitions/for_var"
+        },
+        {
+          "$ref": "#/definitions/for_matrix"
         }
       ]
     },
@@ -467,6 +470,12 @@
       "additionalProperties": false,
       "required": ["var"]
     },
+    "for_matrix": {
+      "description": "A matrix of values to iterate over",
+      "type": "object",
+      "additionalProperties": true,
+      "required": ["matrix"]
+    },
     "precondition": {
       "anyOf": [
         {