move MutatingWalker to new subpackage, exhaustively implement all cases

main.go

@@ -10,6 +10,8 @@ import (
 
 	"github.com/z7zmey/php-parser/parser"
 	"github.com/z7zmey/php-parser/visitor"
+
+	"php2go/parseutil"
 )
 
 func ConvertFile(filename string) (string, error) {
@@ -48,7 +50,14 @@ func ConvertFile(filename string) (string, error) {
 	}
 
 	// Pass 1: Normalise Alt** Stmt types
-	walkMutate(&n, normaliseAltCb)
+	normaliser := parseutil.MutatingWalker{
+		EnterNode: normaliseAltCb,
+		LeaveNode: parseutil.MutatingWalkerNoop,
+	}
+	err = normaliser.Walk(&n)
+	if err != nil {
+		return "", err
+	}
 
 	// Debug pass: Walk and print JSON...
 	if fh, err := os.OpenFile(filename+`.parse2.json`, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644); err == nil {

mutatingwalker.go

@@ -1,54 +0,0 @@
-package main
-
-import (
-	//	"fmt"
-	//"io/ioutil"
-
-	"github.com/z7zmey/php-parser/node"
-	"github.com/z7zmey/php-parser/node/stmt"
-	//"github.com/z7zmey/php-parser/walker"
-)
-
-func walkMutate(n_ *node.Node, cb func(*node.Node)) {
-
-	// Mutate in-place, non recursive...
-	cb(n_)
-
-	// Walk on the mutated version
-	// We must reimplement .Walk() in order to get pointer behaviour
-
-	switch n := (*n_).(type) {
-	case *stmt.StmtList:
-		for i, _ := range n.Stmts {
-			walkMutate(&n.Stmts[i], cb)
-		}
-
-	case *node.Root:
-		for i, _ := range n.Stmts {
-			walkMutate(&n.Stmts[i], cb)
-		}
-
-	case *stmt.If:
-		walkMutate(&n.Cond, cb)
-		walkMutate(&n.Else, cb)
-		for i, _ := range n.ElseIf {
-			walkMutate(&n.ElseIf[i], cb)
-		}
-		walkMutate(&n.Stmt, cb)
-
-	case *stmt.Else:
-		walkMutate(&n.Stmt, cb)
-
-	case *stmt.ElseIf:
-		walkMutate(&n.Cond, cb)
-		walkMutate(&n.Stmt, cb)
-
-	default:
-		// FIXME need to implement Walk() for all node types, to ensure that
-		// we can perform mutation transforms in nested contexts
-		// bail
-		//panic(fmt.Sprintf("walkMutate: unimplemented type '%t'", n))
-
-	}
-
-}

normalisealts.go

@@ -9,7 +9,7 @@ import (
 	//"github.com/z7zmey/php-parser/walker"
 )
 
-func normaliseAltCb(n_ *node.Node) {
+func normaliseAltCb(n_ *node.Node) error {
 
 	switch n := (*n_).(type) {
 	case *stmt.AltIf:
@@ -36,6 +36,8 @@ func normaliseAltCb(n_ *node.Node) {
 		*n_ = elifStmt
 
 	default:
-		return // no change
+		// no change
 	}
+
+	return nil // always
 }

parseutil/Exhaustive.go

@@ -1,4 +1,4 @@
-package main
+package parseutil
 
 import (
 	"fmt"
@@ -215,6 +215,10 @@ type Exhaustive interface {
 func switchExhaustive(e Exhaustive, n_ *node.Node) error {
 	n := *n_ // no copy
 
+	if n == nil {
+		return nil // inner handlers expect a non-nil pointer
+	}
+
 	switch n := n.(type) {
 
 	// node