Add "reduce" option

This addresses issue #185.
mdaines · Aug 21, 2023 · 5c9cbdc · 5c9cbdc
1 parent 584550e
commit 5c9cbdc
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diff --git a/packages/viz/CHANGELOG.md b/packages/viz/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+* Accept a "reduce" option. This has the same effect as using the -x Graphviz command-line option. When using the neato layout engine, it prunes isolated nodes.
+
 * Accept default attributes for graphs, nodes, and edges in render options. This is similar to the -G, -N, -E options provided by the Graphviz command-line.
 
   Setting the default shape for nodes:

diff --git a/packages/viz/src/module/viz.c b/packages/viz/src/module/viz.c
@@ -2,6 +2,7 @@
 #include <emscripten.h>
 
 extern int Y_invert;
+extern unsigned char Reduce;
 
 extern gvplugin_library_t gvplugin_core_LTX_library;
 extern gvplugin_library_t gvplugin_dot_layout_LTX_library;
@@ -19,6 +20,11 @@ void viz_set_y_invert(int value) {
   Y_invert = value;
 }
 
+EMSCRIPTEN_KEEPALIVE
+void viz_set_reduce(int value) {
+  Reduce = value;
+}
+
 EMSCRIPTEN_KEEPALIVE
 char *viz_get_graphviz_version() {
   GVC_t *context = NULL;

diff --git a/packages/viz/src/viz.mjs b/packages/viz/src/viz.mjs
@@ -158,6 +158,7 @@ function renderInput(module, input, options) {
     }
 
     module.ccall("viz_set_y_invert", "number", ["number"], [options.yInvert ? 1 : 0]);
+    module.ccall("viz_set_reduce", "number", ["number"], [options.reduce ? 1 : 0]);
 
     resultPointer = module.ccall("viz_render_graph", "number", ["number", "string", "string"], [graphPointer, options.format, options.engine]);
 

diff --git a/packages/viz/test/standalone.test.mjs b/packages/viz/test/standalone.test.mjs
@@ -135,6 +135,20 @@ describe("standalone", function() {
         });
       });
 
+      it("accepts reduce option", function() {
+        const result = viz.render("graph { a }", { engine: "neato", reduce: true });
+
+        assert.deepStrictEqual(result, {
+          status: "success",
+          output: `graph {
+	graph [bb="0,0,0,0"];
+	node [label="\\N"];
+}
+`,
+          errors: []
+        });
+      });
+
       it("accepts default attributes", function() {
         const result = viz.render("graph {}", {
           defaultAttributes: {

diff --git a/packages/viz/types/index.d.ts b/packages/viz/types/index.d.ts
@@ -37,6 +37,7 @@ export type RenderOptions = {
   format?: string;
   engine?: string;
   yInvert?: boolean;
+  reduce?: boolean;
   defaultAttributes?: DefaultAttributes
 };