Adding ability to use '$ref' to refer to external code files

test/examples/code-ref/code.py

@@ -0,0 +1,4 @@
+
+def update(x):
+    x["value"] = x["value"] + 1
+    return x

test/examples/code-ref/pipeline.yaml

@@ -0,0 +1,26 @@
+
+class: Playbook
+name: codeTest
+
+inputs:
+  startData:
+    embedded:
+      - {"value": 0, "name": "alice"}
+      - {"value": 1, "name": "bob"}
+      - {"value": 2, "name": "charlie"}
+
+
+pipelines:
+  codeTest:
+    - from: startData
+    - map:
+        method: update
+        gpython:
+          $ref: code.py
+    - map:
+        method: update
+        gpython: |
+          def update(x):
+            x["value"] = x["value"] + 1
+            return x
+    - debug: {}

transform/code_block.go

@@ -0,0 +1,45 @@
+package transform
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+type CodeBlock struct {
+	Code    string
+	Ref     string
+	BaseDir string
+}
+
+func (cb *CodeBlock) UnmarshalJSON(data []byte) error {
+	if err := json.Unmarshal(data, &cb.Code); err == nil {
+		return nil
+	}
+	ref := map[string]any{}
+	if err := json.Unmarshal(data, &ref); err == nil {
+		if path, ok := ref["$ref"]; ok {
+			if pathStr, ok := path.(string); ok {
+				cb.Ref = pathStr
+				return nil
+			}
+		}
+	}
+	return fmt.Errorf("unknown code block type")
+}
+
+func (cb *CodeBlock) SetBaseDir(path string) {
+	cb.BaseDir = path
+}
+
+func (cb *CodeBlock) String() string {
+	if cb.Ref != "" {
+		path := filepath.Join(cb.BaseDir, cb.Ref)
+		data, err := os.ReadFile(path)
+		if err == nil {
+			cb.Code = string(data)
+		}
+	}
+	return cb.Code
+}

transform/mapping.go

@@ -11,9 +11,9 @@ import (
 )
 
 type MapStep struct {
-	Method  string `json:"method" jsonschema_description:"Name of function to call"`
-	Python  string `json:"python" jsonschema_description:"Python code to be run"`
-	GPython string `json:"gpython" jsonschema_description:"Python code to be run using GPython"`
+	Method  string     `json:"method" jsonschema_description:"Name of function to call"`
+	Python  string     `json:"python" jsonschema_description:"Python code to be run"`
+	GPython *CodeBlock `json:"gpython" jsonschema_description:"Python code to be run using GPython"`
 }
 
 type mapProcess struct {
@@ -30,10 +30,11 @@ func (ms *MapStep) Init(task task.RuntimeTask) (Processor, error) {
 			log.Printf("Compile Error: %s", err)
 		}
 		return &mapProcess{ms, c}, nil
-	} else if ms.GPython != "" {
+	} else if ms.GPython != nil {
 		log.Printf("Init Map: %s", ms.GPython)
+		ms.GPython.SetBaseDir(task.BaseDir())
 		e := evaluate.GetEngine("gpython", task.WorkDir())
-		c, err := e.Compile(ms.GPython, ms.Method)
+		c, err := e.Compile(ms.GPython.String(), ms.Method)
 		if err != nil {
 			log.Printf("Compile Error: %s", err)
 		}