OAS: Generate parameter patterns (#837)

* Figure out decimal pattern

* More pre-loaded

* Tune predefined spec

* Prefix and suffix detected

* Implement entry compacting

* God bless unit tests

* Fix a bug

* REsearch it more

* Write back test file

* Working on merging pathObjs

* Working on merging ops

* Commit

* Roll back some changes

* Fix test

* Fixed sorting

* Accept test file

* adding end line in the end of the file

Co-authored-by: Igor Gov <iggvrv@gmail.com>

agent/pkg/oas/utils.go

@@ -290,6 +290,53 @@ func longestCommonXfix(strs [][]string, pre bool) []string { // https://github.c
 	return xfix
 }
 
+func longestCommonXfixStr(strs []string, pre bool) string { // https://github.com/jpillora/longestcommon
+	//short-circuit empty list
+	if len(strs) == 0 {
+		return ""
+	}
+	xfix := strs[0]
+	//short-circuit single-element list
+	if len(strs) == 1 {
+		return xfix
+	}
+	//compare first to rest
+	for _, str := range strs[1:] {
+		xfixl := len(xfix)
+		strl := len(str)
+		//short-circuit empty strings
+		if xfixl == 0 || strl == 0 {
+			return ""
+		}
+		//maximum possible length
+		maxl := xfixl
+		if strl < maxl {
+			maxl = strl
+		}
+		//compare letters
+		if pre {
+			//prefix, iterate left to right
+			for i := 0; i < maxl; i++ {
+				if xfix[i] != str[i] {
+					xfix = xfix[:i]
+					break
+				}
+			}
+		} else {
+			//suffix, iternate right to left
+			for i := 0; i < maxl; i++ {
+				xi := xfixl - i - 1
+				si := strl - i - 1
+				if xfix[xi] != str[si] {
+					xfix = xfix[xi+1:]
+					break
+				}
+			}
+		}
+	}
+	return xfix
+}
+
 func getSimilarPrefix(strs []string) string {
 	chunked := make([][]string, 0)
 	for _, item := range strs {