Add string/triml, string/trimr, and string/trim.

src/boot/boot.janet

@@ -1,5 +1,5 @@
 # The core janet library
-# Copyright 2019 (C) Calvin Rose
+# Copyright 2019 © Calvin Rose
 
 ###
 ###

src/core/string.c

@@ -467,6 +467,60 @@ static Janet cfun_string_format(int32_t argc, Janet *argv) {
     return janet_stringv(buffer->data, buffer->count);
 }
 
+static int trim_help_checkset(JanetByteView set, uint8_t x) {
+    for (int32_t j = 0; j < set.len; j++)
+        if (set.bytes[j] == x)
+            return 1;
+    return 0;
+}
+
+static int32_t trim_help_leftedge(JanetByteView str, JanetByteView set) {
+    for (int32_t i = 0; i < str.len; i++)
+        if (!trim_help_checkset(set, str.bytes[i]))
+            return i;
+    return str.len;
+}
+
+static int32_t trim_help_rightedge(JanetByteView str, JanetByteView set) {
+    for (int32_t i = str.len - 1; i >= 0; i--)
+        if (!trim_help_checkset(set, str.bytes[i]))
+            return i + 1;
+    return 0;
+}
+
+static void trim_help_args(int32_t argc, Janet *argv, JanetByteView *str, JanetByteView *set) {
+    janet_arity(argc, 1, 2);
+    *str = janet_getbytes(argv, 0);
+    if (argc >= 2) {
+        *set = janet_getbytes(argv, 1);
+    } else {
+        set->bytes = (const uint8_t *)(" \t\r\n\v\f");
+        set->len = 6;
+    }
+}
+
+static Janet cfun_string_trim(int32_t argc, Janet *argv) {
+    JanetByteView str, set;
+    trim_help_args(argc, argv, &str, &set);
+    int32_t left_edge = trim_help_leftedge(str, set);
+    int32_t right_edge = trim_help_rightedge(str, set);
+    return janet_stringv(str.bytes + left_edge, right_edge - left_edge);
+}
+
+static Janet cfun_string_triml(int32_t argc, Janet *argv) {
+    JanetByteView str, set;
+    trim_help_args(argc, argv, &str, &set);
+    int32_t left_edge = trim_help_leftedge(str, set);
+    return janet_stringv(str.bytes + left_edge, str.len - left_edge);
+}
+
+static Janet cfun_string_trimr(int32_t argc, Janet *argv) {
+    JanetByteView str, set;
+    trim_help_args(argc, argv, &str, &set);
+    int32_t right_edge = trim_help_rightedge(str, set);
+    return janet_stringv(str.bytes, right_edge);
+}
+
 static const JanetReg string_cfuns[] = {
     {
         "string/slice", cfun_string_slice,
@@ -574,6 +628,24 @@ static const JanetReg string_cfuns[] = {
              "Similar to snprintf, but specialized for operating with janet. Returns "
              "a new string.")
     },
+    {
+        "string/trim", cfun_string_trim,
+        JDOC("(string/trim str [,set])\n\n"
+             "Trim leading and trailing whitespace from a byte sequence. If the argument "
+             "set is provided, consider only characters in set to be whitespace.")
+    },
+    {
+        "string/triml", cfun_string_triml,
+        JDOC("(string/triml str [,set])\n\n"
+             "Trim leading whitespace from a byte sequence. If the argument "
+             "set is provided, consider only characters in set to be whitespace.")
+    },
+    {
+        "string/trimr", cfun_string_trimr,
+        JDOC("(string/trimr str [,set])\n\n"
+             "Trim trailing whitespace from a byte sequence. If the argument "
+             "set is provided, consider only characters in set to be whitespace.")
+    },
     {NULL, NULL, NULL}
 };
 

test/suite2.janet

@@ -83,6 +83,16 @@
 (assert (= (string/join @["one" "two" "three"] ", ") "one, two, three") "string/join 2")
 (assert (= (string/join @["one" "two" "three"]) "onetwothree") "string/join 3")
 (assert (= (string/join @[] "hi") "") "string/join 4")
+(assert (= (string/trim " abcd ") "abcd") "string/trim 1")
+(assert (= (string/trim "abcd \t\t\r\f") "abcd") "string/trim 2")
+(assert (= (string/trim "\n\n\t abcd") "abcd") "string/trim 3")
+(assert (= (string/trim "") "") "string/trim 4")
+(assert (= (string/triml " abcd ") "abcd ") "string/triml 1")
+(assert (= (string/triml "\tabcd \t\t\r\f") "abcd \t\t\r\f") "string/triml 2")
+(assert (= (string/triml "abcd ") "abcd ") "string/triml 3")
+(assert (= (string/trimr " abcd ") " abcd") "string/trimr 1")
+(assert (= (string/trimr "\tabcd \t\t\r\f") "\tabcd") "string/trimr 2")
+(assert (= (string/trimr " abcd") " abcd") "string/trimr 3")
 (assert (deep= (string/split "," "one,two,three") @["one" "two" "three"]) "string/split 1")
 (assert (deep= (string/split "," "onetwothree") @["onetwothree"]) "string/split 2")
 (assert (deep= (string/find-all "e" "onetwothree") @[2 9 10]) "string/find-all 1")