Add trimstr/1 function (#3319)

Author: mihaigmarin

docs/content/manual/dev/manual.yml

@@ -1798,6 +1798,17 @@ sections:
             input: '["fo", "foo", "barfoo", "foobar", "foob"]'
             output: ['["fo","","bar","foobar","foob"]']
 
+      - title: "`trimstr(str)`"
+        body: |
+
+          Outputs its input with the given string removed at both ends, if it
+          starts or ends with it.
+
+        examples:
+          - program: '[.[]|trimstr("foo")]'
+            input: '["fo", "foo", "barfoo", "foobarfoo", "foob"]'
+            output: ['["fo","","bar","bar","b"]']
+
       - title: "`trim`, `ltrim`, `rtrim`"
         body: |
 

jq.1.prebuilt

@@ -76,6 +76,7 @@ def fromdate: fromdateiso8601;
 def todate: todateiso8601;
 def ltrimstr($left): if startswith($left) then .[$left | length:] end;
 def rtrimstr($right): if endswith($right) then .[:$right | -length] end;
+def trimstr($val): ltrimstr($val) | rtrimstr($val);
 def match(re; mode): _match_impl(re; mode; false)|.[];
 def match($val): ($val|type) as $vt | if $vt == "string" then match($val; null)
    elif $vt == "array" and ($val | length) > 1 then match($val[0]; $val[1])

src/builtin.jq

@@ -1508,6 +1508,10 @@ split("")
 ["fo", "foo", "barfoo", "foobar", "foob"]
 ["fo","","bar","foobar","foob"]
 
+[.[]|trimstr("foo")]
+["fo", "foo", "barfoo", "foobarfoo", "foob"]
+["fo","","bar","bar","b"]
+
 [(index(","), rindex(",")), indices(",")]
 "a,bc,def,ghij,klmno"
 [1,13,[1,4,8,13]]