node: support namespace, support tracking package imports

main.go

@@ -21,7 +21,9 @@ func ConvertFile(filename string) (string, error) {
 
 	namespaces := visitor.NewNamespaceResolver()
 	// scope := NewScope()
-	state := conversionState{}
+	state := conversionState{
+		importPackages: make(map[string]struct{}),
+	}
 
 	p, err := parser.NewParser([]byte(inputFile), "7.4")
 	if err != nil {

node.go

@@ -39,6 +39,7 @@ type conversionState struct {
 	currentClassName       string
 	currentClassParentName string
 	currentErrHandler      string
+	importPackages         map[string]struct{}
 }
 
 //
@@ -95,40 +96,71 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 	//
 
 	case *node.Root:
-		ret := "package main\n\n"
 
 		// Hoist all declarations first, and put any top-level code into a generated main() function
+		declarations := []string{}
 		statements := []string{}
+		packageName := `main`
 
 		for _, s := range n.Stmts {
 
-			switch s.(type) {
+			switch s := s.(type) {
 			case *stmt.Class, *stmt.Function, *stmt.Interface:
 				this.currentErrHandler = "return nil, err\n"
 
+				sm, err := this.convert(s)
+				if err != nil {
+					return "", parseErr{s, err}
+				}
+
+				// Declaration - emit immediately (hoist)
+				declarations = append(declarations, sm)
+
+			case *stmt.Namespace:
+				if len(s.Stmts) > 0 {
+					return "", parseErr{s, fmt.Errorf("please use `namespace Foo;` instead of blocks")}
+				}
+				namespace, err := this.resolveName(s.NamespaceName)
+				if err != nil {
+					return "", err
+				}
+				packageName = namespace
+
 			default:
 				this.currentErrHandler = "panic(err)\n" // top-level init/main behaviour
-			}
 
-			sm, err := this.convert(s)
-			if err != nil {
-				return "", parseErr{s, err}
-			}
+				sm, err := this.convert(s)
+				if err != nil {
+					return "", parseErr{s, err}
+				}
 
-			switch s.(type) {
-			case *stmt.Class, *stmt.Function, *stmt.Interface:
-				// Declaration - emit immediately (hoist)
-				ret += sm + "\n"
-
-			default:
 				// Top-level function code - deter emission
 				statements = append(statements, sm)
 			}
+
+		}
+
+		// Emit
+		ret := "package main\n\n"
+		if len(this.importPackages) > 0 {
+			ret += "import (\n"
+			for packageName, _ := range this.importPackages {
+				ret += "\t" + strconv.Quote(packageName) + "\n"
+			}
+			ret += ")\n"
+		}
+
+		if len(declarations) > 0 {
+			ret += strings.Join(declarations, "\n") + "\n"
 		}
 
-		// Emit deferred statements
 		if len(statements) > 0 {
-			ret += "func init() {\n"
+			topFunc := `init`
+			if packageName == `main` {
+				topFunc = `main`
+			}
+
+			ret += "func " + topFunc + "() {\n"
 			ret += "\t" + strings.Join(statements, "\t") // Statements already added their own newline
 			ret += "}\n"
 		}
@@ -568,6 +600,9 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 
 			args = append(args, exprGo)
 		}
+
+		this.importPackages["fmt"] = struct{}{}
+
 		return "fmt.Print(" + strings.Join(args, ", ") + ")\n", nil // newline - standalone statement
 
 	case *stmt.InlineHtml:
@@ -582,6 +617,8 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 			quoted = strconv.Quote(n.Value)
 		}
 
+		this.importPackages["fmt"] = struct{}{}
+
 		return "fmt.Print(" + quoted + ")\n", nil // newline - standalone statement
 
 	case *stmt.If:
@@ -697,6 +734,7 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 
 						catchVars = append(catchVars, tempCatchVar+"*"+typename)
 
+						this.importPackages["errors"] = struct{}{}
 						catchStmt := "if errors.As(err, &" + tempCatchVar + ") {\n"
 						if len(catch.Types) > 1 {
 							catchStmt += catchVar + " := " + tempCatchVar + " // rename\n"
@@ -969,6 +1007,7 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 			return "", parseErr{n, err}
 		}
 
+		this.importPackages["math"] = struct{}{}
 		return `math.Mod(` + rval + `, ` + modulo + `)`, nil
 
 	case *binary.Mul:
@@ -996,6 +1035,7 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 			return "", parseErr{n, err}
 		}
 
+		this.importPackages["math"] = struct{}{}
 		return `math.Pow(` + base + `, ` + exponent + `)`, nil
 
 	case *binary.ShiftLeft: