Make the various from_str functions return options

So that they can be used with user input without causing task
failures.

Closes #1335

Author: marijnh

src/comp/metadata/decoder.rs

@@ -95,13 +95,8 @@ fn variant_enum_id(d: ebml::doc) -> ast::def_id {
 }
 
 fn variant_disr_val(d: ebml::doc) -> option<int> {
-    alt ebml::maybe_get_doc(d, tag_disr_val) {
-      some(val_doc) {
-        let val_buf = ebml::doc_data(val_doc);
-        let val = int::parse_buf(val_buf, 10u);
-        ret some(val);
-      }
-      _ { ret none;}
+    option::chain(ebml::maybe_get_doc(d, tag_disr_val)) {|val_doc|
+        int::parse_buf(ebml::doc_data(val_doc), 10u)
     }
 }
 

src/comp/metadata/tydecode.rs

@@ -390,8 +390,8 @@ fn parse_def_id(buf: [u8]) -> ast::def_id {
     for b: u8 in crate_part { crate_part_vec += [b]; }
     for b: u8 in def_part { def_part_vec += [b]; }
 
-    let crate_num = uint::parse_buf(crate_part_vec, 10u) as int;
-    let def_num = uint::parse_buf(def_part_vec, 10u) as int;
+    let crate_num = option::get(uint::parse_buf(crate_part_vec, 10u)) as int;
+    let def_num = option::get(uint::parse_buf(def_part_vec, 10u)) as int;
     ret {crate: crate_num, node: def_num};
 }
 

src/comp/syntax/ast_util.rs

@@ -301,7 +301,7 @@ fn lit_to_const(lit: @lit) -> const_val {
       lit_str(s) { const_str(s) }
       lit_int(n, _) { const_int(n) }
       lit_uint(n, _) { const_uint(n) }
-      lit_float(n, _) { const_float(float::from_str(n)) }
+      lit_float(n, _) { const_float(option::get(float::from_str(n))) }
       lit_nil { const_int(0i64) }
       lit_bool(b) { const_int(b as i64) }
     }

src/comp/syntax/parse/lexer.rs

@@ -174,8 +174,8 @@ fn scan_digits(rdr: reader, radix: uint) -> str {
     while true {
         let c = rdr.curr;
         if c == '_' { rdr.bump(); cont; }
-        alt char::maybe_digit(c) {
-          some(d) if (d as uint) < radix {
+        alt char::to_digit(c, radix) {
+          some(d) {
             str::push_char(rslt, c);
             rdr.bump();
           }
@@ -229,7 +229,7 @@ fn scan_number(c: char, rdr: reader) -> token::token {
         if str::len_bytes(num_str) == 0u {
             rdr.fatal("no valid digits found for number");
         }
-        let parsed = u64::from_str(num_str, base as u64);
+        let parsed = option::get(u64::from_str(num_str, base as u64));
         alt tp {
           either::left(t) { ret token::LIT_INT(parsed as i64, t); }
           either::right(t) { ret token::LIT_UINT(parsed, t); }
@@ -276,7 +276,7 @@ fn scan_number(c: char, rdr: reader) -> token::token {
         if str::len_bytes(num_str) == 0u {
             rdr.fatal("no valid digits found for number");
         }
-        let parsed = u64::from_str(num_str, base as u64);
+        let parsed = option::get(u64::from_str(num_str, base as u64));
         ret token::LIT_INT(parsed as i64, ast::ty_i);
     }
 }

src/libcore/bool.rs

@@ -59,11 +59,11 @@ pure fn is_false(v: t) -> bool { !v }
 #[doc(
   brief = "Parse logic value from `s`"
 )]
-pure fn from_str(s: str) -> t {
+pure fn from_str(s: str) -> option<t> {
     alt check s {
-      "true" { true }
-      "false" { false }
-      _ { fail "'" + s + "' is not a valid boolean string"; }
+      "true" { some(true) }
+      "false" { some(false) }
+      _ { none }
     }
 }
 
@@ -89,7 +89,7 @@ pure fn to_bit(v: t) -> u8 { if v { 1u8 } else { 0u8 } }
 #[test]
 fn test_bool_from_str() {
     all_values { |v|
-        assert v == from_str(bool::to_str(v))
+        assert some(v) == from_str(bool::to_str(v))
     }
 }
 

src/libcore/char.rs

@@ -38,7 +38,7 @@ export is_alphabetic,
        is_lowercase, is_uppercase,
        is_whitespace, is_alphanumeric,
        is_ascii, is_digit,
-       to_digit, to_lower, to_upper, maybe_digit, cmp;
+       to_digit, to_lower, to_upper, cmp;
 
 import is_alphabetic = unicode::derived_property::Alphabetic;
 import is_XID_start = unicode::derived_property::XID_Start;
@@ -102,26 +102,18 @@ pure fn is_digit(c: char) -> bool {
            Safety note: This function fails if `c` is not a valid char",
   return = "If `c` is between '0' and '9', the corresponding value \
             between 0 and 9. If `c` is 'a' or 'A', 10. If `c` is \
-            'b' or 'B', 11, etc."
+            'b' or 'B', 11, etc. Returns none if the char does not \
+            refer to a digit in the given radix."
 )]
-pure fn to_digit(c: char) -> u8 unsafe {
-    alt maybe_digit(c) {
-      option::some(x) { x }
-      option::none { fail; }
-    }
-}
-
-#[doc(
-  brief = "Convert a char to the corresponding digit. Returns none when \
-           character is not a valid hexadecimal digit."
-)]
-pure fn maybe_digit(c: char) -> option<u8> {
-    alt c {
-      '0' to '9' { option::some(c as u8 - ('0' as u8)) }
-      'a' to 'z' { option::some(c as u8 + 10u8 - ('a' as u8)) }
-      'A' to 'Z' { option::some(c as u8 + 10u8 - ('A' as u8)) }
-      _ { option::none }
-    }
+pure fn to_digit(c: char, radix: uint) -> option<uint> {
+    let val = alt c {
+      '0' to '9' { c as uint - ('0' as uint) }
+      'a' to 'z' { c as uint + 10u - ('a' as uint) }
+      'A' to 'Z' { c as uint + 10u - ('A' as uint) }
+      _ { ret none; }
+    };
+    if val < radix { some(val) }
+    else { none }
 }
 
 /*
@@ -192,30 +184,19 @@ fn test_is_whitespace() {
 
 #[test]
 fn test_to_digit() {
-    assert (to_digit('0') == 0u8);
-    assert (to_digit('1') == 1u8);
-    assert (to_digit('2') == 2u8);
-    assert (to_digit('9') == 9u8);
-    assert (to_digit('a') == 10u8);
-    assert (to_digit('A') == 10u8);
-    assert (to_digit('b') == 11u8);
-    assert (to_digit('B') == 11u8);
-    assert (to_digit('z') == 35u8);
-    assert (to_digit('Z') == 35u8);
-}
-
-#[test]
-#[should_fail]
-#[ignore(cfg(target_os = "win32"))]
-fn test_to_digit_fail_1() {
-    to_digit(' ');
-}
-
-#[test]
-#[should_fail]
-#[ignore(cfg(target_os = "win32"))]
-fn test_to_digit_fail_2() {
-    to_digit('$');
+    assert to_digit('0', 10u) == some(0u);
+    assert to_digit('1', 2u) == some(1u);
+    assert to_digit('2', 3u) == some(2u);
+    assert to_digit('9', 10u) == some(9u);
+    assert to_digit('a', 16u) == some(10u);
+    assert to_digit('A', 16u) == some(10u);
+    assert to_digit('b', 16u) == some(11u);
+    assert to_digit('B', 16u) == some(11u);
+    assert to_digit('z', 36u) == some(35u);
+    assert to_digit('Z', 36u) == some(35u);
+
+    assert to_digit(' ', 10u) == none;
+    assert to_digit('$', 36u) == none;
 }
 
 #[test]

src/libcore/float.rs

@@ -122,28 +122,27 @@ Leading and trailing whitespace are ignored.
 
 Parameters:
 
-num - A string, possibly empty.
+num - A string
 
 Returns:
 
-<NaN> If the string did not represent a valid number.
-Otherwise, the floating-point number represented [num].
+none if the string did not represent a valid number.
+Otherwise, some(n) where n is the floating-point
+number represented by [num].
 */
-fn from_str(num: str) -> float {
-   let num = str::trim(num);
-
+fn from_str(num: str) -> option<float> {
    let pos = 0u;                  //Current byte position in the string.
                                   //Used to walk the string in O(n).
    let len = str::len_bytes(num);  //Length of the string, in bytes.
 
-   if len == 0u { ret 0.; }
+   if len == 0u { ret none; }
    let total = 0f;                //Accumulated result
    let c     = 'z';               //Latest char.
 
    //The string must start with one of the following characters.
    alt str::char_at(num, 0u) {
       '-' | '+' | '0' to '9' | '.' {}
-      _ { ret NaN; }
+      _ { ret none; }
    }
 
    //Determine if first char is '-'/'+'. Set [pos] and [neg] accordingly.
@@ -173,7 +172,7 @@ fn from_str(num: str) -> float {
            break;
          }
          _ {
-           ret NaN;
+           ret none;
          }
        }
    }
@@ -193,7 +192,7 @@ fn from_str(num: str) -> float {
                  break;
              }
              _ {
-                 ret NaN;
+                 ret none;
              }
          }
       }
@@ -238,17 +237,17 @@ fn from_str(num: str) -> float {
              total = total * multiplier;
           }
       } else {
-         ret NaN;
+         ret none;
       }
    }
 
    if(pos < len) {
-     ret NaN;
+     ret none;
    } else {
      if(neg) {
         total *= -1f;
      }
-     ret total;
+     ret some(total);
    }
 }
 
@@ -291,39 +290,36 @@ fn pow_uint_to_uint_as_float(x: uint, pow: uint) -> float {
 
 #[test]
 fn test_from_str() {
-   assert ( from_str("3") == 3. );
-   assert ( from_str("  3  ") == 3. );
-   assert ( from_str("3.14") == 3.14 );
-   assert ( from_str("+3.14") == 3.14 );
-   assert ( from_str("-3.14") == -3.14 );
-   assert ( from_str("2.5E10") == 25000000000. );
-   assert ( from_str("2.5e10") == 25000000000. );
-   assert ( from_str("25000000000.E-10") == 2.5 );
-   assert ( from_str("") == 0. );
-   assert ( from_str(".") == 0. );
-   assert ( from_str(".e1") == 0. );
-   assert ( from_str(".e-1") == 0. );
-   assert ( from_str("5.") == 5. );
-   assert ( from_str(".5") == 0.5 );
-   assert ( from_str("0.5") == 0.5 );
-   assert ( from_str("0.5 ") == 0.5 );
-   assert ( from_str(" 0.5 ") == 0.5 );
-   assert ( from_str(" -.5 ") == -0.5 );
-   assert ( from_str(" -.5 ") == -0.5 );
-   assert ( from_str(" -5 ") == -5. );
-
-   assert ( is_NaN(from_str("x")) );
-   assert ( from_str(" ") == 0. );
-   assert ( from_str("   ") == 0. );
-   assert ( from_str(" 0.5") == 0.5 );
-   assert ( from_str(" 0.5 ") == 0.5 );
-   assert ( from_str(" .1 ") == 0.1 );
-   assert ( is_NaN(from_str("e")) );
-   assert ( is_NaN(from_str("E")) );
-   assert ( is_NaN(from_str("E1")) );
-   assert ( is_NaN(from_str("1e1e1")) );
-   assert ( is_NaN(from_str("1e1.1")) );
-   assert ( is_NaN(from_str("1e1-1")) );
+   assert from_str("3") == some(3.);
+   assert from_str("3") == some(3.);
+   assert from_str("3.14") == some(3.14);
+   assert from_str("+3.14") == some(3.14);
+   assert from_str("-3.14") == some(-3.14);
+   assert from_str("2.5E10") == some(25000000000.);
+   assert from_str("2.5e10") == some(25000000000.);
+   assert from_str("25000000000.E-10") == some(2.5);
+   assert from_str(".") == some(0.);
+   assert from_str(".e1") == some(0.);
+   assert from_str(".e-1") == some(0.);
+   assert from_str("5.") == some(5.);
+   assert from_str(".5") == some(0.5);
+   assert from_str("0.5") == some(0.5);
+   assert from_str("0.5") == some(0.5);
+   assert from_str("0.5") == some(0.5);
+   assert from_str("-.5") == some(-0.5);
+   assert from_str("-.5") == some(-0.5);
+   assert from_str("-5") == some(-5.);
+
+   assert from_str("") == none;
+   assert from_str("x") == none;
+   assert from_str(" ") == none;
+   assert from_str("   ") == none;
+   assert from_str("e") == none;
+   assert from_str("E") == none;
+   assert from_str("E1") == none;
+   assert from_str("1e1e1") == none;
+   assert from_str("1e1.1") == none;
+   assert from_str("1e1-1") == none;
 }
 
 #[test]