[PATCH] std: Added signed number support to atoi().

[Jordan Yelloz]

For example, it's now possible to get the number -10 as a result of calling
atoi("-10") or 239 as a result of calling atoi("+ef", 16).

2021-12-03  Jordan Yelloz  <jordan@yelloz.me>

        * libpoke/std.pk (atoi): Added code that extracts any single leading '+'
        or '-', decides a polarity of the number to parse, and shifts over the
        input string by 1 character if necessary before parsing the digits.
        * testsuite/poke.std/std-test.pk: Added tests for new behaviors.
---
 libpoke/std.pk                 | 23 +++++++++++++++++++++--
 testsuite/poke.std/std-test.pk | 12 ++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/libpoke/std.pk b/libpoke/std.pk
index bd38b7e1b527..178968c9bee5 100644
--- a/libpoke/std.pk
+++ b/libpoke/std.pk
@@ -90,18 +90,37 @@ fun atoi = (string s, int<32> b = 10) int<64>:
          ((c >= 'a') && (c <= 'f')) || ((c >= 'A') && (c <= 'F'));
       }
 
+    fun signchar = (string str) int<8>:
+      {
+        if (str'length > 1) return str[0];
+        return 0;
+      }
+
+    fun signum = (uint<8> c) int<32>:
+      {
+        if (c == '-') return -1;
+        if (c == '+') return +1;
+        return 0;
+      }
+
     if (!(b in [2, 8, 10, 16]))
       raise E_inval;
 
+    var sign = signum(signchar(s));
+    if (sign == 0)
+      sign = +1;
+    else
+      s = s[1:];
+
     for (c in s)
     {
       if (!valid(c, b))
-        return result;
+        break;
 
       result = result * b + htoi(c);
     }
 
-    return result;
+    return sign * result;
   }
 
 fun ltos = (int<64> i, uint<32> base = 10) string:
diff --git a/testsuite/poke.std/std-test.pk b/testsuite/poke.std/std-test.pk
index 5de5afb65589..8654c07ba496 100644
--- a/testsuite/poke.std/std-test.pk
+++ b/testsuite/poke.std/std-test.pk
@@ -24,19 +24,31 @@ var tests = [
     func = lambda (string name) void:
       {
         assert (atoi ("0", 2) == 0L);
+        assert (atoi ("+0", 2) == 0L);
+        assert (atoi ("-0", 2) == 0L);
         assert (atoi ("1", 2) == 1L);
+        assert (atoi ("+1", 2) == 1L);
+        assert (atoi ("-1", 2) == -1L);
         assert (atoi ("111111111", 2) == 511L);
         assert (atoi ("x", 2) == 0L);
+        assert (atoi ("+x", 2) == 0L);
+        assert (atoi ("-x", 2) == 0L);
         assert (atoi ("1111x234", 2) == 15L);
 
         assert (atoi ("1777", 8) == 1023L);
+        assert (atoi ("+1777", 8) == 1023L);
+        assert (atoi ("-1777", 8) == -1023L);
 
         assert (atoi ("1777", 10) == 1777L);
         assert (atoi ("1777") == 1777L);
+        assert (atoi ("+1777") == 1777L);
+        assert (atoi ("-1777") == -1777L);
 
         assert (atoi ("fce2", 16) == 64738L);
         assert (atoi ("bEeF", 16) == 48879L);
         assert (atoi ("deadbeef", 16) == 0xdeadbeef);
+        assert (atoi ("+deadbeef", 16) == 0xdeadbeef);
+        assert (atoi ("-deadbeef", 16) == -0xdeadbeef);
       },
   },
   PkTest {
-- 
2.34.1