[Go] Add %go_import directive.

CHANGES.current

@@ -5,6 +5,9 @@ See the RELEASENOTES file for a summary of changes in each release.
 Version 3.0.0 (in progress)
 ============================
 
+2014-01-21: ianlancetaylor
+	    [Go] Add %go_import directive.
+
 2014-01-21: ianlancetaylor
 	    [Go] Add support for Go 1.3, not yet released.
 

Doc/Manual/Go.html

@@ -666,9 +666,31 @@ func (arg SwigcptrWrapped_MyClass) GetAValue() (int, bool) {
 few, then you might as well define your own struct that includes the
 swig-wrapped object, instead of adding methods to the swig-generated object.</p>
 
-<p>This only works if your wrappers do not need to import other go modules.
+<p>If you need to import other go packages, you can do this with
-There is at present no way to insert import statements in the correct place
+<code>%go_import</code>.  For example,</p>
-in swig-generated go.  If you need to do that, you must put your go code
+<div class="code">
-in a separate file.</p>
+<pre>
+%go_import("fmt", _ "unusedPackage", rp "renamed/package")
+
+%insert(go_wrapper) %{
+
+func foo() {
+  fmt.Println("Some string:", rp.GetString())
+}
+
+// Importing the same package twice is permitted,
+// Go code will be generated with only the first instance of the import.
+%go_import("fmt")
+
+%insert(go_wrapper) %{
+
+func bar() {
+  fmt.Println("Hello world!")
+}
+
+%}
+</pre>
+</div>
+
 </body>
 </html>

Lib/go/go.swg

@@ -4,6 +4,9 @@
  * Go configuration module.
  * ------------------------------------------------------------ */
 
+/* Code insertion directives */
+#define %go_import(...) %insert(go_imports) %{__VA_ARGS__%}
+
 /* Basic types */
 
 %typemap(gotype) bool,               const bool &               "bool"

Lib/go/goruntime.swg

@@ -192,30 +192,26 @@ static _gostring_ _swig_makegostring(const char *p, size_t l) {
 
 #ifndef SWIGGO_GCCGO
 
-%insert(go_header) %{
+%go_import("unsafe", _ "runtime/cgo")
-
-import _ "runtime/cgo"
-import "unsafe"
-
-type _ unsafe.Pointer
-
-%}
 
 #else
 
+%go_import("syscall", "unsafe")
+
 %insert(go_header) %{
 
-import "syscall"
-import "unsafe"
-
 type _ syscall.Sockaddr
 
-type _ unsafe.Pointer
-
 %}
 
 #endif
 
+%insert(go_header) %{
+
+type _ unsafe.Pointer
+
+%}
+
 /* Function pointers are translated by the code in go.cxx into
    _swig_fnptr.  Member pointers are translated to _swig_memberptr.  */
 

Source/Modules/go.cxx

@@ -45,6 +45,7 @@ class GO:public Language {
   File *f_c_init;
   File *f_c_directors;
   File *f_c_directors_h;
+  File *f_go_imports;
   File *f_go_runtime;
   File *f_go_header;
   File *f_go_wrappers;
@@ -84,6 +85,9 @@ class GO:public Language {
   // A hash table of classes which were defined.  The index is a Go
   // type name.
   Hash *defined_types;
+  // A hash table of all the go_imports already imported. The index is a full
+  // import name e.g. '"runtime"' or '_ "runtime/cgo"' or 'sc "syscall"'.
+  Hash *go_imports;
 
 public:
   GO():package(NULL),
@@ -104,6 +108,7 @@ public:
      f_c_init(NULL),
      f_c_directors(NULL),
      f_c_directors_h(NULL),
+     f_go_imports(NULL),
      f_go_runtime(NULL),
      f_go_header(NULL),
      f_go_wrappers(NULL),
@@ -120,7 +125,8 @@ public:
      making_variable_wrappers(false),
      is_static_member_function(false),
      undefined_types(NULL),
-     defined_types(NULL) {
+     defined_types(NULL),
+     go_imports(NULL) {
     director_multiple_inheritance = 1;
     director_language = 1;
     director_prot_ctor_code = NewString("_swig_gopanic(\"accessing abstract class or protected constructor\");");
@@ -362,6 +368,7 @@ private:
     f_c_wrappers = NewString("");
     f_c_init = NewString("");
     f_c_directors = NewString("");
+    f_go_imports = NewString("");
     f_go_runtime = NewString("");
     f_go_header = NewString("");
     f_go_wrappers = NewString("");
@@ -379,6 +386,7 @@ private:
     Swig_register_filebyname("director", f_c_directors);
     Swig_register_filebyname("director_h", f_c_directors_h);
     Swig_register_filebyname("go_begin", f_go_begin);
+    Swig_register_filebyname("go_imports", f_go_imports);
     Swig_register_filebyname("go_runtime", f_go_runtime);
     Swig_register_filebyname("go_header", f_go_header);
     Swig_register_filebyname("go_wrapper", f_go_wrappers);
@@ -445,11 +453,14 @@ private:
 
     undefined_types = NewHash();
     defined_types = NewHash();
+    go_imports = NewHash();
 
     // Emit code.
 
     Language::top(n);
 
+    Delete(go_imports);
+
     // Write out definitions for the types not defined by SWIG.
 
     Printv(f_go_wrappers, "\n", NULL);
@@ -493,6 +504,7 @@ private:
     Dump(f_c_runtime, f_c_begin);
     Dump(f_c_wrappers, f_c_begin);
     Dump(f_c_init, f_c_begin);
+    Dump(f_go_imports, f_go_begin);
     Dump(f_go_header, f_go_begin);
     Dump(f_go_runtime, f_go_begin);
     Dump(f_go_wrappers, f_go_begin);
@@ -506,6 +518,7 @@ private:
     Delete(f_c_header);
     Delete(f_c_wrappers);
     Delete(f_c_init);
+    Delete(f_go_imports);
     Delete(f_go_runtime);
     Delete(f_go_header);
     Delete(f_go_wrappers);
@@ -535,7 +548,10 @@ private:
     String *hold_import = imported_package;
     String *modname = Getattr(n, "module");
     if (modname) {
-      Printv(f_go_begin, "import \"", modname, "\"\n", NULL);
+      if (!Getattr(go_imports, modname)) {
+        Setattr(go_imports, modname, modname);
+        Printv(f_go_imports, "import \"", modname, "\"\n", NULL);
+      }
       imported_package = modname;
       saw_import = true;
     }
@@ -544,6 +560,31 @@ private:
     return r;
   }
 
+  /* ----------------------------------------------------------------------
+   * Language::insertDirective()
+   *
+   * If the section is go_imports, store them for later.
+   * ---------------------------------------------------------------------- */
+  virtual int insertDirective(Node *n) {
+    char *section = Char(Getattr(n, "section"));
+    if ((ImportMode && !Getattr(n, "generated")) ||
+        !section || (strcmp(section, "go_imports") != 0)) {
+      return Language::insertDirective(n);
+    }
+
+    char *code = Char(Getattr(n, "code"));
+    char *pch = strtok(code, ",");
+    while (pch != NULL) {
+      // Do not import same thing more than once.
+      if (!Getattr(go_imports, pch)) {
+        Setattr(go_imports, pch, pch);
+        Printv(f_go_imports, "import ", pch, "\n", NULL);
+      }
+      pch = strtok(NULL, ",");
+    }
+    return SWIG_OK;
+  }
+
   /* ----------------------------------------------------------------------
    * functionWrapper()
    *