Moving engine to gf JSON files as an optional entry

README.md

@@ -89,13 +89,18 @@ alias the gf binary to something else, or `unalias gf` to remove the `git fetch`
 There are some amazing code searching engines out there that can be a better replacement for grep.
 A good example is [the silver searcher](https://github.com/ggreer/the_silver_searcher).
 It's faster (like **way faster**) and presents the results in a more visually digestible manner.
-In order to utilize a different engine, use `-engine` and provide a different tool like so:
+In order to utilize a different engine, add `engine: <other tool>` to the relevant pattern file:
 ```bash
-# Using the silver searcher instead of grep
-gf -engine ag api-keys
+# Using the silver searcher instead of grep for the aws-keys pattern:
+# 1. Adding "ag" engine
+# 2. Removing the E flag which is irrelevant for ag
+{
+  "engine": "ag",
+  "flags": "-Hanr",
+  "pattern": "([^A-Z0-9]|^)(AKIA|A3T|AGPA|AIDA|AROA|AIPA|ANPA|ANVA|ASIA)[A-Z0-9]{12,}"
+}
 ```
-* Note I: Different engines use different flags, so in the example above, the flag `E` has to be removed from the `api-keys.json` file in order of ag to successfully run.
-* Note II: You'd probably want to `alias <command>='gf -engine <engine>'` if you plan to use this regularly.
+* Note: Different engines use different flags, so in the example above, the flag `E` has to be removed from the `aws-keys.json` file in order for ag to successfully run.
 
 
 ## Install

main.go

@@ -16,6 +16,7 @@ type pattern struct {
 	Flags    string   `json:"flags,omitempty"`
 	Pattern  string   `json:"pattern,omitempty"`
 	Patterns []string `json:"patterns,omitempty"`
+	Engine   string   `json:"engine,omitempty"`
 }
 
 func main() {
@@ -28,9 +29,6 @@ func main() {
 	var dumpMode bool
 	flag.BoolVar(&dumpMode, "dump", false, "prints the grep command rather than executing it")
 
-	var engine string
-	flag.StringVar(&engine, "engine", "grep", "uses a different engine instead of grep e.g. ag")
-
 	flag.Parse()
 
 	if listMode {
@@ -102,8 +100,8 @@ func main() {
 	} else {
 		var cmd *exec.Cmd
 		operator := "grep"
-		if engine != "" {
-			operator = engine
+		if pat.Engine != "" {
+			operator = pat.Engine
 		}
 
 		if stdinIsPipe() {