Formating: support specifying costant strings

doc/json_schema.json

@@ -578,6 +578,13 @@
                     "type": "boolean",
                     "description": "Whether to disable the stdout application buffer",
                     "default": false
+                },
+                "constants": {
+                    "type": "array",
+                    "description": "List of strings to be used in custom format of modules",
+                    "items": {
+                        "type": "string"
+                    }
                 }
             }
         },

src/common/format.c

@@ -244,6 +244,27 @@ void ffParseFormatString(FFstrbuf* buffer, const FFstrbuf* formatstr, uint32_t n
             continue;
         }
 
+        //test for constant, if so evaluate it
+        if (firstChar == '$')
+        {
+            char* pend = NULL;
+            int32_t indexSigned = (int32_t) strtol(placeholderValue.chars + 1, &pend, 10);
+            uint32_t index = (uint32_t) indexSigned;
+            bool backward = indexSigned < 0;
+
+            if (indexSigned == 0 || *pend != '\0' || instance.config.display.constants.length < index)
+            {
+                appendInvalidPlaceholder(buffer, "{", &placeholderValue, i, formatstr->length);
+                continue;
+            }
+
+            FFstrbuf* item = FF_LIST_GET(FFstrbuf, instance.config.display.constants, backward
+                ? instance.config.display.constants.length - index
+                : index - 1);
+            ffStrbufAppend(buffer, item);
+            continue;
+        }
+
         int32_t truncLength = INT32_MAX;
         char* pColon = memchr(placeholderValue.chars, ':', placeholderValue.length);
         if (pColon != NULL)

src/options/display.c

@@ -199,6 +199,15 @@ const char* ffOptionsParseDisplayJsonConfig(FFOptionsDisplay* options, yyjson_va
             options->noBuffer = yyjson_get_bool(val);
         else if (ffStrEqualsIgnCase(key, "keyWidth"))
             options->keyWidth = (uint32_t) yyjson_get_uint(val);
+        else if (ffStrEqualsIgnCase(key, "constants"))
+        {
+            if (!yyjson_is_arr(val))
+                return "display.constants must be an array";
+            yyjson_val* item;
+            size_t idx, max;
+            yyjson_arr_foreach(val, idx, max, item)
+                ffStrbufInitS(ffListAdd(&options->constants), yyjson_get_str(item));
+        }
         else if (ffStrEqualsIgnCase(key, "tsVersion"))
             return "display.tsVersion has been renamed to general.detectVersion";
         else
@@ -404,6 +413,8 @@ void ffOptionsInitDisplay(FFOptionsDisplay* options)
     ffStrbufInitStatic(&options->percentColorGreen, FF_COLOR_FG_GREEN);
     ffStrbufInitStatic(&options->percentColorYellow, instance.state.terminalLightTheme ? FF_COLOR_FG_YELLOW : FF_COLOR_FG_LIGHT_YELLOW);
     ffStrbufInitStatic(&options->percentColorRed, instance.state.terminalLightTheme ? FF_COLOR_FG_RED : FF_COLOR_FG_LIGHT_RED);
+
+    ffListInit(&options->constants, sizeof(FFstrbuf));
 }
 
 void ffOptionsDestroyDisplay(FFOptionsDisplay* options)
@@ -415,6 +426,9 @@ void ffOptionsDestroyDisplay(FFOptionsDisplay* options)
     ffStrbufDestroy(&options->keyValueSeparator);
     ffStrbufDestroy(&options->barCharElapsed);
     ffStrbufDestroy(&options->barCharTotal);
+    FF_LIST_FOR_EACH(FFstrbuf, item, options->constants)
+        ffStrbufDestroy(item);
+    ffListDestroy(&options->constants);
 }
 
 void ffOptionsGenerateDisplayJsonConfig(FFOptionsDisplay* options, yyjson_mut_doc* doc)

src/options/display.h

@@ -53,6 +53,7 @@ typedef struct FFOptionsDisplay
     FFstrbuf percentColorRed;
     bool noBuffer;
     uint32_t keyWidth;
+    FFlist constants; // list of FFstrbuf
 } FFOptionsDisplay;
 
 const char* ffOptionsParseDisplayJsonConfig(FFOptionsDisplay* options, yyjson_val* root);