Fix that a previous error would cause an exception to be thrown on va…

…lid input. This addresses #49. Thanks to @caseywatts for reporting this.
mdaines · Oct 30, 2015 · f595d85 · f595d85
1 parent ba12882
commit f595d85
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Showing 3 changed files with 27 additions and 9 deletions.
diff --git a/src/post.js b/src/post.js
@@ -1,4 +1,9 @@
   var graphviz;
+  var errors;
+
+  function appendError(buf) {
+    errors += graphviz["Pointer_stringify"](buf);
+  }
 
   function Viz(src) {
     var options = arguments.length <= 1 || arguments[1] === undefined ? {} : arguments[1];
@@ -9,14 +14,14 @@
       graphviz = Module();
     }
 
+    errors = "";
+
     var resultPointer = graphviz["ccall"]("vizRenderFromString", "number", ["string", "string", "string"], [src, format, engine]);
     var resultString = graphviz["Pointer_stringify"](resultPointer);
     graphviz["_free"](resultPointer);
 
-    var lastError = graphviz["ccall"]("aglasterr", "string", [], []);
-
-    if (lastError) {
-      throw lastError;
+    if (errors != "") {
+      throw errors;
     }
 
     return resultString;

diff --git a/src/viz.c b/src/viz.c
@@ -1,11 +1,17 @@
 #include <gvc.h>
+#include <emscripten.h>
 
 extern gvplugin_library_t gvplugin_dot_layout_LTX_library;
 extern gvplugin_library_t gvplugin_neato_layout_LTX_library;
 extern gvplugin_library_t gvplugin_core_LTX_library;
 
 GVC_t *context = NULL;
 
+int vizErrorf(char *buf) {
+  EM_ASM_({ appendError($0); }, buf);
+  return 0;
+}
+
 char* vizRenderFromString(const char *src, const char *format, const char *engine) {
 
   Agraph_t *graph;
@@ -18,9 +24,9 @@ char* vizRenderFromString(const char *src, const char *format, const char *engin
     gvAddLibrary(context, &gvplugin_dot_layout_LTX_library);
     gvAddLibrary(context, &gvplugin_neato_layout_LTX_library);
   }
-  
-  // Don't immediately report errors. Instead, we will ask aglasterr in post.js.
-  agseterr(AGMAX);
+
+  agseterr(AGERR);
+  agseterrf(vizErrorf);
 
   // Reset line numbers.
   agreadline(1);

diff --git a/tests/input.js b/tests/input.js
@@ -1,15 +1,22 @@
 QUnit.module("input");
 
 QUnit.test("result from first graph in input is returned for multiple invocations", function(assert) {
-  var result = Viz("digraph A {} digraph B {}", { format: "xdot" });
+  var result;
+
+  result = Viz("digraph A {} digraph B {}", { format: "xdot" });
   assert.ok(result.match(/digraph A/), "Result should contain \"digraph A\"");
   assert.notOk(result.match(/digraph B/), "Result should not contain \"digraph B\"");
 
-  var result = Viz("digraph B {} digraph A {}", { format: "xdot" });
+  result = Viz("digraph B {} digraph A {}", { format: "xdot" });
   assert.ok(result.match(/digraph B/), "Result should contain \"digraph B\"");
   assert.notOk(result.match(/digraph A/), "Result should not contain \"digraph A\"");
 });
 
+QUnit.test("after throwing an exception on invalid input, do not throw one on valid input", function(assert) {
+  assert.throws(function() { Viz("digraph { \n ->"); });
+  Viz("digraph { a -> b;}");
+});
+
 QUnit.test("syntax error in graph throws exception", function(assert) {
   assert.throws(function() {
     Viz("digraph { \n ->");