(#127) Introduce flag mistake correction mechanism based on levenshtein distance

src/vodus.cpp

@@ -3,6 +3,7 @@
 #include <cstdint>
 #include <cmath>
 #include <ctime>
+#include <climits>
 
 #include <algorithm>
 

src/vodus_video_params.cpp

@@ -121,6 +121,43 @@ void patch_video_params_from_file(Video_Params *params, String_View filepath)
     }
 }
 
+template <typename T>
+T supa_min(T x)
+{
+    return x;
+}
+
+template <typename T, typename... Rest>
+T supa_min(T x, Rest... rest)
+{
+    return min(x, supa_min(rest...));
+}
+
+
+size_t levenshtein(String_View a, String_View b)
+{
+    size_t *dp = new size_t[(a.count + 1) * (b.count + 1)];
+#define DP(row, column) dp[(row) * (b.count + 1) + (column)]
+    defer(delete[] dp);
+    memset(dp, 0, sizeof(size_t) * (a.count + 1) * (b.count + 1));
+
+    for (size_t i = 0; i <= a.count; ++i) {
+        for (size_t j = 0; j <= b.count; ++j) {
+            if (min(i, j) == 0) {
+                DP(i, j) = max(i, j);
+            } else {
+                DP(i, j) = supa_min(
+                    DP(i - 1, j) + 1,
+                    DP(i, j - 1) + 1,
+                    DP(i - 1, j - 1) + (a.data[i - 1] != b.data[j - 1]));
+            }
+        }
+    }
+
+    return DP(a.count, b.count);
+#undef DP
+}
+
 void patch_video_params_from_flag(Video_Params *params, String_View flag, String_View value)
 {
     if (flag == "fps"_sv) {
@@ -153,7 +190,17 @@ void patch_video_params_from_flag(Video_Params *params, String_View flag, String
             abort();
         }
     } else {
-        println(stderr, "Unknown flag `", flag, "`");
+        size_t n = ULONG_MAX;
+        String_View corrected_flag = {};
+        for (size_t i = 0; i < param_names_count; ++i) {
+            auto m = levenshtein(flag, param_names[i]);
+            if (m < n) {
+                n = m;
+                corrected_flag = param_names[i];
+            }
+        }
+
+        println(stderr, "Unknown flag `", flag, "`. Maybe you meant `", corrected_flag, "`");
         abort();
     }
 }

src/vodus_video_params.hpp

@@ -22,6 +22,21 @@ struct Video_Params
     Maybe<size_t> messages_limit;
 };
 
+String_View param_names[] = {
+    "output_type"_sv,
+    "fps"_sv,
+    "width"_sv,
+    "height"_sv,
+    "font_size"_sv,
+    "background_color"_sv,
+    "nickname_color"_sv,
+    "text_color"_sv,
+    "bitrate"_sv,
+    "font"_sv,
+    "messages_limit"_sv,
+};
+const size_t param_names_count = sizeof(param_names) / sizeof(param_names[0]);
+
 void print1(FILE *stream, Video_Params params);
 
 Video_Params default_video_params();