1 files changed, 50 insertions, 0 deletions
diff --git a/functional.c b/functional.c
new file mode 100644
index 0000000..c1577bd
--- /dev/null
+++ b/functional.c
@@ -0,0 +1,50 @@
+#include "functional.h"
+
+void func_map(Functional* f) {
+  f->args.i = 0;
+  f->args.offset = 0;
+  while (f->args.i < f->args.n) {
+    f->map(&f->args);
+    f->args.i++;
+  }
+}
+
+void func_filterGeneric(Functional* f,
+                        void (*shiftLeft)(FunctionalArgs* args)) {
+  bool shouldMutate = shiftLeft != NULL;
+  int nInCollection = 0;
+  for (f->args.i = 0; f->args.i < f->args.n; f->args.i++) {
+    bool shouldInclude = f->filter(&f->args);
+    if (shouldInclude) {
+      f->args.offset = f->args.i - nInCollection;
+      if (!shouldMutate) {
+        f->map(&f->args);
+      }
+      nInCollection++;
+    } else {
+      if (shouldMutate) {
+        shiftLeft(&f->args);
+      }
+    }
+  }
+  f->args.n = nInCollection;
+}
+
+void func_filter(Functional* f) {
+  func_filterGeneric(f, NULL);
+}
+
+void func_filterMutate(Functional* f, void (*shiftLeft)(FunctionalArgs* args)) {
+  func_filterGeneric(f, shiftLeft);
+}
+
+void* func_find(Functional* f) {
+  f->args.i = 0;
+  while (f->args.i < f->args.n) {
+    if (f->filter(&f->args)) {
+      return f->derefInput(f->args.i, f->args.arr);
+    }
+    f->args.i++;
+  }
+  return NULL;
+}