interp: extend dot debugging

cmd/yaegi/yaegi.go

@@ -72,6 +72,11 @@ Debugging support (may be removed at any time):
     Generate and display graphviz dot of AST with dotty(1)
   YAEGI_CFG_DOT=1
     Generate and display graphviz dot of CFG with dotty(1)
+  YAEGI_DOT_CMD='dot -Tsvg -ofoo.svg'
+    Defines how to process the dot code generated whenever YAEGI_AST_DOT and/or
+    YAEGI_CFG_DOT is enabled. If any of YAEGI_AST_DOT or YAEGI_CFG_DOT is set,
+    but YAEGI_DOT_CMD is not defined, the default is to write to a .dot file
+    next to the Go source file.
 */
 package main
 

interp/dot.go

@@ -3,8 +3,10 @@ package interp
 import (
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"os/exec"
+	"path/filepath"
 	"strings"
 )
 
@@ -58,10 +60,19 @@ func (n *node) cfgDot(out io.Writer) {
 	fmt.Fprintf(out, "}\n")
 }
 
-// dotX returns an output stream to a dot(1) co-process where to write data in .dot format
-func dotX() io.WriteCloser {
-	cmd := exec.Command("dotty", "-")
-	//cmd := exec.Command("dot", "-T", "xlib")
+type nopCloser struct {
+	io.Writer
+}
+
+func (nopCloser) Close() error { return nil }
+
+// dotWriter returns an output stream to a dot(1) co-process where to write data in .dot format
+func dotWriter(dotCmd string) io.WriteCloser {
+	if dotCmd == "" {
+		return nopCloser{ioutil.Discard}
+	}
+	fields := strings.Fields(dotCmd)
+	cmd := exec.Command(fields[0], fields[1:]...)
 	dotin, err := cmd.StdinPipe()
 	if err != nil {
 		log.Fatal(err)
@@ -71,3 +82,14 @@ func dotX() io.WriteCloser {
 	}
 	return dotin
 }
+
+func defaultDotCmd(filePath, prefix string) string {
+	dir, fileName := filepath.Split(filePath)
+	ext := filepath.Ext(fileName)
+	if ext == "" {
+		fileName += ".dot"
+	} else {
+		fileName = strings.Replace(fileName, ext, ".dot", 1)
+	}
+	return "dot -Tdot -o" + dir + prefix + fileName
+}

interp/interp.go

@@ -104,8 +104,11 @@ type imports map[string]map[string]*symbol
 
 // opt stores interpreter options
 type opt struct {
-	astDot   bool          // display AST graph (debug)
-	cfgDot   bool          // display CFG graph (debug)
+	astDot bool // display AST graph (debug)
+	cfgDot bool // display CFG graph (debug)
+	// dotCmd is the command to process the dot graph produced when astDot and/or
+	// cfgDot is enabled. It defaults to 'dot -Tdot -o <filename>.dot'.
+	dotCmd   string
 	noRun    bool          // compile, but do not run
 	fastChan bool          // disable cancellable chan operations
 	context  build.Context // build context: GOPATH, build constraints
@@ -224,6 +227,11 @@ func New(options Options) *Interpreter {
 	// cfgDot activates AST graph display for the interpreter
 	i.opt.cfgDot, _ = strconv.ParseBool(os.Getenv("YAEGI_CFG_DOT"))
 
+	// dotCmd defines how to process the dot code generated whenever astDot and/or
+	// cfgDot is enabled. It defaults to 'dot -Tdot -o<filename>.dot' where filename
+	// is context dependent.
+	i.opt.dotCmd = os.Getenv("YAEGI_DOT_CMD")
+
 	// noRun disables the execution (but not the compilation) in the interpreter
 	i.opt.noRun, _ = strconv.ParseBool(os.Getenv("YAEGI_NO_RUN"))
 
@@ -328,7 +336,11 @@ func (interp *Interpreter) Eval(src string) (res reflect.Value, err error) {
 	}
 
 	if interp.astDot {
-		root.astDot(dotX(), interp.Name)
+		dotCmd := interp.dotCmd
+		if dotCmd == "" {
+			dotCmd = defaultDotCmd(interp.Name, "yaegi-ast-")
+		}
+		root.astDot(dotWriter(dotCmd), interp.Name)
 		if interp.noRun {
 			return res, err
 		}
@@ -363,7 +375,11 @@ func (interp *Interpreter) Eval(src string) (res reflect.Value, err error) {
 	interp.mutex.Unlock()
 
 	if interp.cfgDot {
-		root.cfgDot(dotX())
+		dotCmd := interp.dotCmd
+		if dotCmd == "" {
+			dotCmd = defaultDotCmd(interp.Name, "yaegi-cfg-")
+		}
+		root.cfgDot(dotWriter(dotCmd))
 	}
 
 	if interp.noRun {

interp/src.go

@@ -67,8 +67,13 @@ func (interp *Interpreter) importSrc(rPath, path string) error {
 		if root == nil {
 			continue
 		}
+
 		if interp.astDot {
-			root.astDot(dotX(), name)
+			dotCmd := interp.dotCmd
+			if dotCmd == "" {
+				dotCmd = defaultDotCmd(name, "yaegi-ast-")
+			}
+			root.astDot(dotWriter(dotCmd), name)
 		}
 		if pkgName == "" {
 			pkgName = pname