lib/standard/text: Added is_int validation function to Text

Signed-off-by: Lucas Bajolet <r4pass@hotmail.com>

diff --git a/lib/standard/text/abstract_text.nit b/lib/standard/text/abstract_text.nit
index 078cc3c..2df4801 100644 (file)
--- a/lib/standard/text/abstract_text.nit
+++ b/lib/standard/text/abstract_text.nit
@@ -240,7 +240,58 @@ abstract class Text
                return b.to_s
        end
 
-       # If `self` contains only digits, return the corresponding integer
+       # Is `self` a well-formed Integer (i.e. parsable via `to_i`)
+       #
+       #     assert "123".is_int
+       #     assert "0b1011".is_int
+       #     assert not "0x_".is_int
+       #     assert not "0xGE".is_int
+       fun is_int: Bool do
+               var s = remove_all('_')
+               var pos = 0
+               while s[pos] == '-' do
+                       pos += 1
+               end
+               s = s.substring_from(pos)
+               var rets = s.strip_numhead
+               if rets == "" then return false
+               var hd = get_numhead
+               if hd == "0x" or hd == "0X" then return rets.is_hex
+               if hd == "0b" or hd == "0B" then return rets.is_bin
+               if hd == "0o" or hd == "0O" then return rets.is_oct
+               return hd.is_dec
+       end
+
+       # Removes the numeric head of `self` if present
+       #
+       #     intrude import standard::text::abstract_text
+       #     assert "0xFFEF".strip_numhead  == "FFEF"
+       #     assert "0o7364".strip_numhead  == "7364"
+       #     assert "0b01001".strip_numhead == "01001"
+       #     assert "98".strip_numhead      == "98"
+       private fun strip_numhead: Text do
+               if get_numhead != "" then return substring_from(2)
+               return self
+       end
+
+       # Gets the numeric head of `self` if present
+       # Returns "" otherwise
+       #
+       #     intrude import standard::text::abstract_text
+       #     assert "0xFEFF".get_numhead  == "0x"
+       #     assert "0b01001".get_numhead == "0b"
+       #     assert "0o872".get_numhead   == "0o"
+       #     assert "98".get_numhead      == ""
+       private fun get_numhead: Text do
+               if self.length < 2 then return ""
+               var c = self[0]
+               if c != '0' then return ""
+               c = self[1]
+               if c == 'x' or c == 'b' or c == 'o' or
+                  c == 'X' or c == 'B' or c == 'O' then return substring(0, 2)
+               return ""
+       end
+
        #
        #     assert "123".to_i        == 123
        #     assert "-1".to_i         == -1