Add packages/strings/strings.grnd

packages/strings/strings.grnd

@@ -0,0 +1,85 @@
+fun -char !findChar -string &str -char &char
+    set &idx 0
+    getstrsize $str &len
+
+    @loop
+        equal $idx $len &store
+        if $store %end
+        getstrcharat $str $idx &stridx
+        equal $stridx $char &store
+        if $store %return
+        add $idx 1 &idx
+        jump %loop
+
+    @return
+    return $idx
+
+    @end    
+endfun
+
+fun -char !findCharInstance -string &str -char &char -int &instance
+    set &idx 0
+    getstrsize $str &len
+
+    @loop
+        equal $idx $len &store
+        if $store %end
+        getstrcharat $str $idx &stridx
+        equal $stridx $char &store
+        if $store %decrement
+        @increment
+        add $idx 1 &idx
+        jump %loop
+
+    @decrement
+    equal $instance 0 &store
+    if $store %return
+    subtract $instance 1 &instance
+    jump %increment
+
+    @return
+    return $idx
+
+    @end    
+endfun
+
+fun -string !mid -string &str -int &idx -int &len
+    set &ans ""
+    lesser $idx 0 &store
+    if $store %end
+    @loop
+        getstrsize $str &store
+        equal $store $idx &store
+        if $store %end
+        getstrcharat $str $idx &store
+        add $ans $store &ans
+        add $idx 1 &idx
+        getstrsize $ans &store
+        equal $store $len &store
+        if $store %return
+        jump %loop
+
+    @return
+    return $ans
+
+    @end
+endfun
+
+fun -string !inBrackets -string &str -char &left -char &right -int &instance
+    # Get start idx
+    pusharg $str
+    pusharg $left
+    pusharg $instance
+    call !findCharInstance &store
+    stdlnout $store
+endfun
+
+fun -string !matchStart -string &str -string &instr
+    getstrsize $instr &store
+    pusharg $str
+    pusharg 0 
+    pusharg $store
+    call !mid &store
+    equal $store $instr &store
+    return $store
+endfun