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</pre><pre class='rust '>
<span class='comment'>// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT</span>
<span class='comment'>// file at the top-level directory of this distribution and at</span>
<span class='comment'>// http://rust-lang.org/COPYRIGHT.</span>
<span class='comment'>//</span>
<span class='comment'>// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span>
<span class='comment'>// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span>
<span class='comment'>// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your</span>
<span class='comment'>// option. This file may not be copied, modified, or distributed</span>
<span class='comment'>// except according to those terms.</span>
<span class='doccomment'>//! Numeric traits for generic mathematics</span>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>ops</span>::{<span class='ident'>Add</span>, <span class='ident'>Sub</span>, <span class='ident'>Mul</span>, <span class='ident'>Div</span>, <span class='ident'>Rem</span>};
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>bounds</span>::<span class='ident'>Bounded</span>;
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>float</span>::<span class='ident'>Float</span>;
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>identities</span>::{<span class='ident'>Zero</span>, <span class='ident'>One</span>};
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>ops</span>::<span class='ident'>checked</span>::<span class='op'>*</span>;
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>ops</span>::<span class='ident'>saturating</span>::<span class='ident'>Saturating</span>;
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>sign</span>::{<span class='ident'>Signed</span>, <span class='ident'>Unsigned</span>};
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>cast</span>::<span class='op'>*</span>;
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='ident'>int</span>::<span class='ident'>PrimInt</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>identities</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>sign</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>ops</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>bounds</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>float</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>cast</span>;
<span class='kw'>pub</span> <span class='kw'>mod</span> <span class='ident'>int</span>;
<span class='doccomment'>/// The base trait for numeric types</span>
<span class='kw'>pub</span> <span class='kw'>trait</span> <span class='ident'>Num</span>: <span class='ident'>PartialEq</span> <span class='op'>+</span> <span class='ident'>Zero</span> <span class='op'>+</span> <span class='ident'>One</span>
<span class='op'>+</span> <span class='ident'>Add</span><span class='op'><</span><span class='ident'>Output</span> <span class='op'>=</span> <span class='self'>Self</span><span class='op'>></span> <span class='op'>+</span> <span class='ident'>Sub</span><span class='op'><</span><span class='ident'>Output</span> <span class='op'>=</span> <span class='self'>Self</span><span class='op'>></span>
<span class='op'>+</span> <span class='ident'>Mul</span><span class='op'><</span><span class='ident'>Output</span> <span class='op'>=</span> <span class='self'>Self</span><span class='op'>></span> <span class='op'>+</span> <span class='ident'>Div</span><span class='op'><</span><span class='ident'>Output</span> <span class='op'>=</span> <span class='self'>Self</span><span class='op'>></span> <span class='op'>+</span> <span class='ident'>Rem</span><span class='op'><</span><span class='ident'>Output</span> <span class='op'>=</span> <span class='self'>Self</span><span class='op'>></span>
{
<span class='kw'>type</span> <span class='ident'>FromStrRadixErr</span>;
<span class='doccomment'>/// Convert from a string and radix <= 36.</span>
<span class='kw'>fn</span> <span class='ident'>from_str_radix</span>(<span class='ident'>str</span>: <span class='kw-2'>&</span><span class='ident'>str</span>, <span class='ident'>radix</span>: <span class='ident'>u32</span>) <span class='op'>-></span> <span class='prelude-ty'>Result</span><span class='op'><</span><span class='self'>Self</span>, <span class='self'>Self</span>::<span class='ident'>FromStrRadixErr</span><span class='op'>></span>;
}
<span class='macro'>macro_rules</span><span class='macro'>!</span> <span class='ident'>int_trait_impl</span> {
(<span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>name</span>:<span class='ident'>ident</span> <span class='kw'>for</span> $(<span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>:<span class='ident'>ty</span>)<span class='op'>*</span>) <span class='op'>=></span> ($(
<span class='kw'>impl</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>name</span> <span class='kw'>for</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span> {
<span class='kw'>type</span> <span class='ident'>FromStrRadixErr</span> <span class='op'>=</span> ::<span class='ident'>std</span>::<span class='ident'>num</span>::<span class='ident'>ParseIntError</span>;
<span class='kw'>fn</span> <span class='ident'>from_str_radix</span>(<span class='ident'>s</span>: <span class='kw-2'>&</span><span class='ident'>str</span>, <span class='ident'>radix</span>: <span class='ident'>u32</span>)
<span class='op'>-></span> <span class='prelude-ty'>Result</span><span class='op'><</span><span class='self'>Self</span>, ::<span class='ident'>std</span>::<span class='ident'>num</span>::<span class='ident'>ParseIntError</span><span class='op'>></span>
{
<span class='op'><</span><span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span><span class='op'>></span>::<span class='ident'>from_str_radix</span>(<span class='ident'>s</span>, <span class='ident'>radix</span>)
}
}
)<span class='op'>*</span>)
}
<span class='macro'>int_trait_impl</span><span class='macro'>!</span>(<span class='ident'>Num</span> <span class='kw'>for</span> <span class='ident'>usize</span> <span class='ident'>u8</span> <span class='ident'>u16</span> <span class='ident'>u32</span> <span class='ident'>u64</span> <span class='ident'>isize</span> <span class='ident'>i8</span> <span class='ident'>i16</span> <span class='ident'>i32</span> <span class='ident'>i64</span>);
<span class='attribute'>#[<span class='ident'>derive</span>(<span class='ident'>Debug</span>)]</span>
<span class='kw'>pub</span> <span class='kw'>enum</span> <span class='ident'>FloatErrorKind</span> {
<span class='ident'>Empty</span>,
<span class='ident'>Invalid</span>,
}
<span class='comment'>// FIXME: std::num::ParseFloatError is stable in 1.0, but opaque to us,</span>
<span class='comment'>// so there's not really any way for us to reuse it.</span>
<span class='attribute'>#[<span class='ident'>derive</span>(<span class='ident'>Debug</span>)]</span>
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>ParseFloatError</span> {
<span class='kw'>pub</span> <span class='ident'>kind</span>: <span class='ident'>FloatErrorKind</span>,
}
<span class='comment'>// FIXME: The standard library from_str_radix on floats was deprecated, so we're stuck</span>
<span class='comment'>// with this implementation ourselves until we want to make a breaking change.</span>
<span class='comment'>// (would have to drop it from `Num` though)</span>
<span class='macro'>macro_rules</span><span class='macro'>!</span> <span class='ident'>float_trait_impl</span> {
(<span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>name</span>:<span class='ident'>ident</span> <span class='kw'>for</span> $(<span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>:<span class='ident'>ty</span>)<span class='op'>*</span>) <span class='op'>=></span> ($(
<span class='kw'>impl</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>name</span> <span class='kw'>for</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span> {
<span class='kw'>type</span> <span class='ident'>FromStrRadixErr</span> <span class='op'>=</span> <span class='ident'>ParseFloatError</span>;
<span class='kw'>fn</span> <span class='ident'>from_str_radix</span>(<span class='ident'>src</span>: <span class='kw-2'>&</span><span class='ident'>str</span>, <span class='ident'>radix</span>: <span class='ident'>u32</span>)
<span class='op'>-></span> <span class='prelude-ty'>Result</span><span class='op'><</span><span class='self'>Self</span>, <span class='self'>Self</span>::<span class='ident'>FromStrRadixErr</span><span class='op'>></span>
{
<span class='kw'>use</span> <span class='self'>self</span>::<span class='ident'>FloatErrorKind</span>::<span class='op'>*</span>;
<span class='kw'>use</span> <span class='self'>self</span>::<span class='ident'>ParseFloatError</span> <span class='kw'>as</span> <span class='ident'>PFE</span>;
<span class='comment'>// Special values</span>
<span class='kw'>match</span> <span class='ident'>src</span> {
<span class='string'>"inf"</span> <span class='op'>=></span> <span class='kw'>return</span> <span class='prelude-val'>Ok</span>(<span class='ident'>Float</span>::<span class='ident'>infinity</span>()),
<span class='string'>"-inf"</span> <span class='op'>=></span> <span class='kw'>return</span> <span class='prelude-val'>Ok</span>(<span class='ident'>Float</span>::<span class='ident'>neg_infinity</span>()),
<span class='string'>"NaN"</span> <span class='op'>=></span> <span class='kw'>return</span> <span class='prelude-val'>Ok</span>(<span class='ident'>Float</span>::<span class='ident'>nan</span>()),
_ <span class='op'>=></span> {},
}
<span class='kw'>fn</span> <span class='ident'>slice_shift_char</span>(<span class='ident'>src</span>: <span class='kw-2'>&</span><span class='ident'>str</span>) <span class='op'>-></span> <span class='prelude-ty'>Option</span><span class='op'><</span>(<span class='ident'>char</span>, <span class='kw-2'>&</span><span class='ident'>str</span>)<span class='op'>></span> {
<span class='ident'>src</span>.<span class='ident'>chars</span>().<span class='ident'>nth</span>(<span class='number'>0</span>).<span class='ident'>map</span>(<span class='op'>|</span><span class='ident'>ch</span><span class='op'>|</span> (<span class='ident'>ch</span>, <span class='kw-2'>&</span><span class='ident'>src</span>[<span class='number'>1</span>..]))
}
<span class='kw'>let</span> (<span class='ident'>is_positive</span>, <span class='ident'>src</span>) <span class='op'>=</span> <span class='kw'>match</span> <span class='ident'>slice_shift_char</span>(<span class='ident'>src</span>) {
<span class='prelude-val'>None</span> <span class='op'>=></span> <span class='kw'>return</span> <span class='prelude-val'>Err</span>(<span class='ident'>PFE</span> { <span class='ident'>kind</span>: <span class='ident'>Empty</span> }),
<span class='prelude-val'>Some</span>((<span class='string'>'-'</span>, <span class='string'>""</span>)) <span class='op'>=></span> <span class='kw'>return</span> <span class='prelude-val'>Err</span>(<span class='ident'>PFE</span> { <span class='ident'>kind</span>: <span class='ident'>Empty</span> }),
<span class='prelude-val'>Some</span>((<span class='string'>'-'</span>, <span class='ident'>src</span>)) <span class='op'>=></span> (<span class='bool-val'>false</span>, <span class='ident'>src</span>),
<span class='prelude-val'>Some</span>((_, _)) <span class='op'>=></span> (<span class='bool-val'>true</span>, <span class='ident'>src</span>),
};
<span class='comment'>// The significand to accumulate</span>
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>sig</span> <span class='op'>=</span> <span class='kw'>if</span> <span class='ident'>is_positive</span> { <span class='number'>0.0</span> } <span class='kw'>else</span> { <span class='op'>-</span><span class='number'>0.0</span> };
<span class='comment'>// Necessary to detect overflow</span>
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>prev_sig</span> <span class='op'>=</span> <span class='ident'>sig</span>;
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>cs</span> <span class='op'>=</span> <span class='ident'>src</span>.<span class='ident'>chars</span>().<span class='ident'>enumerate</span>();
<span class='comment'>// Exponent prefix and exponent index offset</span>
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>exp_info</span> <span class='op'>=</span> <span class='prelude-val'>None</span>::<span class='op'><</span>(<span class='ident'>char</span>, <span class='ident'>usize</span>)<span class='op'>></span>;
<span class='comment'>// Parse the integer part of the significand</span>
<span class='kw'>for</span> (<span class='ident'>i</span>, <span class='ident'>c</span>) <span class='kw'>in</span> <span class='ident'>cs</span>.<span class='ident'>by_ref</span>() {
<span class='kw'>match</span> <span class='ident'>c</span>.<span class='ident'>to_digit</span>(<span class='ident'>radix</span>) {
<span class='prelude-val'>Some</span>(<span class='ident'>digit</span>) <span class='op'>=></span> {
<span class='comment'>// shift significand one digit left</span>
<span class='ident'>sig</span> <span class='op'>=</span> <span class='ident'>sig</span> <span class='op'>*</span> (<span class='ident'>radix</span> <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>);
<span class='comment'>// add/subtract current digit depending on sign</span>
<span class='kw'>if</span> <span class='ident'>is_positive</span> {
<span class='ident'>sig</span> <span class='op'>=</span> <span class='ident'>sig</span> <span class='op'>+</span> ((<span class='ident'>digit</span> <span class='kw'>as</span> <span class='ident'>isize</span>) <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>);
} <span class='kw'>else</span> {
<span class='ident'>sig</span> <span class='op'>=</span> <span class='ident'>sig</span> <span class='op'>-</span> ((<span class='ident'>digit</span> <span class='kw'>as</span> <span class='ident'>isize</span>) <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>);
}
<span class='comment'>// Detect overflow by comparing to last value, except</span>
<span class='comment'>// if we've not seen any non-zero digits.</span>
<span class='kw'>if</span> <span class='ident'>prev_sig</span> <span class='op'>!=</span> <span class='number'>0.0</span> {
<span class='kw'>if</span> <span class='ident'>is_positive</span> <span class='op'>&&</span> <span class='ident'>sig</span> <span class='op'><=</span> <span class='ident'>prev_sig</span>
{ <span class='kw'>return</span> <span class='prelude-val'>Ok</span>(<span class='ident'>Float</span>::<span class='ident'>infinity</span>()); }
<span class='kw'>if</span> <span class='op'>!</span><span class='ident'>is_positive</span> <span class='op'>&&</span> <span class='ident'>sig</span> <span class='op'>>=</span> <span class='ident'>prev_sig</span>
{ <span class='kw'>return</span> <span class='prelude-val'>Ok</span>(<span class='ident'>Float</span>::<span class='ident'>neg_infinity</span>()); }
<span class='comment'>// Detect overflow by reversing the shift-and-add process</span>
<span class='kw'>if</span> <span class='ident'>is_positive</span> <span class='op'>&&</span> (<span class='ident'>prev_sig</span> <span class='op'>!=</span> (<span class='ident'>sig</span> <span class='op'>-</span> <span class='ident'>digit</span> <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>) <span class='op'>/</span> <span class='ident'>radix</span> <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>)
{ <span class='kw'>return</span> <span class='prelude-val'>Ok</span>(<span class='ident'>Float</span>::<span class='ident'>infinity</span>()); }
<span class='kw'>if</span> <span class='op'>!</span><span class='ident'>is_positive</span> <span class='op'>&&</span> (<span class='ident'>prev_sig</span> <span class='op'>!=</span> (<span class='ident'>sig</span> <span class='op'>+</span> <span class='ident'>digit</span> <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>) <span class='op'>/</span> <span class='ident'>radix</span> <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>)
{ <span class='kw'>return</span> <span class='prelude-val'>Ok</span>(<span class='ident'>Float</span>::<span class='ident'>neg_infinity</span>()); }
}
<span class='ident'>prev_sig</span> <span class='op'>=</span> <span class='ident'>sig</span>;
},
<span class='prelude-val'>None</span> <span class='op'>=></span> <span class='kw'>match</span> <span class='ident'>c</span> {
<span class='string'>'e'</span> <span class='op'>|</span> <span class='string'>'E'</span> <span class='op'>|</span> <span class='string'>'p'</span> <span class='op'>|</span> <span class='string'>'P'</span> <span class='op'>=></span> {
<span class='ident'>exp_info</span> <span class='op'>=</span> <span class='prelude-val'>Some</span>((<span class='ident'>c</span>, <span class='ident'>i</span> <span class='op'>+</span> <span class='number'>1</span>));
<span class='kw'>break</span>; <span class='comment'>// start of exponent</span>
},
<span class='string'>'.'</span> <span class='op'>=></span> {
<span class='kw'>break</span>; <span class='comment'>// start of fractional part</span>
},
_ <span class='op'>=></span> {
<span class='kw'>return</span> <span class='prelude-val'>Err</span>(<span class='ident'>PFE</span> { <span class='ident'>kind</span>: <span class='ident'>Invalid</span> });
},
},
}
}
<span class='comment'>// If we are not yet at the exponent parse the fractional</span>
<span class='comment'>// part of the significand</span>
<span class='kw'>if</span> <span class='ident'>exp_info</span>.<span class='ident'>is_none</span>() {
<span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>power</span> <span class='op'>=</span> <span class='number'>1.0</span>;
<span class='kw'>for</span> (<span class='ident'>i</span>, <span class='ident'>c</span>) <span class='kw'>in</span> <span class='ident'>cs</span>.<span class='ident'>by_ref</span>() {
<span class='kw'>match</span> <span class='ident'>c</span>.<span class='ident'>to_digit</span>(<span class='ident'>radix</span>) {
<span class='prelude-val'>Some</span>(<span class='ident'>digit</span>) <span class='op'>=></span> {
<span class='comment'>// Decrease power one order of magnitude</span>
<span class='ident'>power</span> <span class='op'>=</span> <span class='ident'>power</span> <span class='op'>/</span> (<span class='ident'>radix</span> <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>);
<span class='comment'>// add/subtract current digit depending on sign</span>
<span class='ident'>sig</span> <span class='op'>=</span> <span class='kw'>if</span> <span class='ident'>is_positive</span> {
<span class='ident'>sig</span> <span class='op'>+</span> (<span class='ident'>digit</span> <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>) <span class='op'>*</span> <span class='ident'>power</span>
} <span class='kw'>else</span> {
<span class='ident'>sig</span> <span class='op'>-</span> (<span class='ident'>digit</span> <span class='kw'>as</span> <span class='macro-nonterminal'>$</span><span class='macro-nonterminal'>t</span>) <span class='op'>*</span> <span class='ident'>power</span>
};
<span class='comment'>// Detect overflow by comparing to last value</span>
<span class='kw'>if</span> <span class='ident'>is_positive</span> <span class='op'>&&</span> <span class='ident'>sig</span> <span class='op'><</span> <span class='ident'>prev_sig</span>
{ <span class='kw'>return</span> <span class='prelude-val'>Ok</span>(<span class='ident'>Float</span>::<span class='ident'>infinity</span>()); }
<span class='kw'>if</span> <span class='op'>!</span><span class='ident'>is_positive</span> <span class='op'>&&</span> <span class='ident'>sig</span> <span class='op'>></span> <span class='ident'>prev_sig</span>
{ <span class='kw'>return</span> <span class='prelude-val'>Ok</span>(<span class='ident'>Float</span>::<span class='ident'>neg_infinity</span>()); }
<span class='ident'>prev_sig</span> <span class='op'>=</span> <span class='ident'>sig</span>;
},
<span class='prelude-val'>None</span> <span class='op'>=></span> <span class='kw'>match</span> <span class='ident'>c</span> {
<span class='string'>'e'</span> <span class='op'>|</span> <span class='string'>'E'</span> <span class='op'>|</span> <span class='string'>'p'</span> <span class='op'>|</span> <span class='string'>'P'</span> <span class='op'>=></span> {
<span class='ident'>exp_info</span> <span class='op'>=</span> <span class='prelude-val'>Some</span>((<span class='ident'>c</span>, <span class='ident'>i</span> <span class='op'>+</span> <span class='number'>1</span>));
<span class='kw'>break</span>; <span class='comment'>// start of exponent</span>
},
_ <span class='op'>=></span> {
<span class='kw'>return</span> <span class='prelude-val'>Err</span>(<span class='ident'>PFE</span> { <span class='ident'>kind</span>: <span class='ident'>Invalid</span> });
},
},
}
}
}
<span class='comment'>// Parse and calculate the exponent</span>
<span class='kw'>let</span> <span class='ident'>exp</span> <span class='op'>=</span> <span class='kw'>match</span> <span class='ident'>exp_info</span> {
<span class='prelude-val'>Some</span>((<span class='ident'>c</span>, <span class='ident'>offset</span>)) <span class='op'>=></span> {
<span class='kw'>let</span> <span class='ident'>base</span> <span class='op'>=</span> <span class='kw'>match</span> <span class='ident'>c</span> {
<span class='string'>'E'</span> <span class='op'>|</span> <span class='string'>'e'</span> <span class='kw'>if</span> <span class='ident'>radix</span> <span class='op'>==</span> <span class='number'>10</span> <span class='op'>=></span> <span class='number'>10.0</span>,
<span class='string'>'P'</span> <span class='op'>|</span> <span class='string'>'p'</span> <span class='kw'>if</span> <span class='ident'>radix</span> <span class='op'>==</span> <span class='number'>16</span> <span class='op'>=></span> <span class='number'>2.0</span>,
_ <span class='op'>=></span> <span class='kw'>return</span> <span class='prelude-val'>Err</span>(<span class='ident'>PFE</span> { <span class='ident'>kind</span>: <span class='ident'>Invalid</span> }),
};
<span class='comment'>// Parse the exponent as decimal integer</span>
<span class='kw'>let</span> <span class='ident'>src</span> <span class='op'>=</span> <span class='kw-2'>&</span><span class='ident'>src</span>[<span class='ident'>offset</span>..];
<span class='kw'>let</span> (<span class='ident'>is_positive</span>, <span class='ident'>exp</span>) <span class='op'>=</span> <span class='kw'>match</span> <span class='ident'>slice_shift_char</span>(<span class='ident'>src</span>) {
<span class='prelude-val'>Some</span>((<span class='string'>'-'</span>, <span class='ident'>src</span>)) <span class='op'>=></span> (<span class='bool-val'>false</span>, <span class='ident'>src</span>.<span class='ident'>parse</span>::<span class='op'><</span><span class='ident'>usize</span><span class='op'>></span>()),
<span class='prelude-val'>Some</span>((<span class='string'>'+'</span>, <span class='ident'>src</span>)) <span class='op'>=></span> (<span class='bool-val'>true</span>, <span class='ident'>src</span>.<span class='ident'>parse</span>::<span class='op'><</span><span class='ident'>usize</span><span class='op'>></span>()),
<span class='prelude-val'>Some</span>((_, _)) <span class='op'>=></span> (<span class='bool-val'>true</span>, <span class='ident'>src</span>.<span class='ident'>parse</span>::<span class='op'><</span><span class='ident'>usize</span><span class='op'>></span>()),
<span class='prelude-val'>None</span> <span class='op'>=></span> <span class='kw'>return</span> <span class='prelude-val'>Err</span>(<span class='ident'>PFE</span> { <span class='ident'>kind</span>: <span class='ident'>Invalid</span> }),
};
<span class='kw'>match</span> (<span class='ident'>is_positive</span>, <span class='ident'>exp</span>) {
(<span class='bool-val'>true</span>, <span class='prelude-val'>Ok</span>(<span class='ident'>exp</span>)) <span class='op'>=></span> <span class='ident'>base</span>.<span class='ident'>powi</span>(<span class='ident'>exp</span> <span class='kw'>as</span> <span class='ident'>i32</span>),
(<span class='bool-val'>false</span>, <span class='prelude-val'>Ok</span>(<span class='ident'>exp</span>)) <span class='op'>=></span> <span class='number'>1.0</span> <span class='op'>/</span> <span class='ident'>base</span>.<span class='ident'>powi</span>(<span class='ident'>exp</span> <span class='kw'>as</span> <span class='ident'>i32</span>),
(_, <span class='prelude-val'>Err</span>(_)) <span class='op'>=></span> <span class='kw'>return</span> <span class='prelude-val'>Err</span>(<span class='ident'>PFE</span> { <span class='ident'>kind</span>: <span class='ident'>Invalid</span> }),
}
},
<span class='prelude-val'>None</span> <span class='op'>=></span> <span class='number'>1.0</span>, <span class='comment'>// no exponent</span>
};
<span class='prelude-val'>Ok</span>(<span class='ident'>sig</span> <span class='op'>*</span> <span class='ident'>exp</span>)
}
}
)<span class='op'>*</span>)
}
<span class='macro'>float_trait_impl</span><span class='macro'>!</span>(<span class='ident'>Num</span> <span class='kw'>for</span> <span class='ident'>f32</span> <span class='ident'>f64</span>);
<span class='attribute'>#[<span class='ident'>test</span>]</span>
<span class='kw'>fn</span> <span class='ident'>from_str_radix_unwrap</span>() {
<span class='comment'>// The Result error must impl Debug to allow unwrap()</span>
<span class='kw'>let</span> <span class='ident'>i</span>: <span class='ident'>i32</span> <span class='op'>=</span> <span class='ident'>Num</span>::<span class='ident'>from_str_radix</span>(<span class='string'>"0"</span>, <span class='number'>10</span>).<span class='ident'>unwrap</span>();
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>i</span>, <span class='number'>0</span>);
<span class='kw'>let</span> <span class='ident'>f</span>: <span class='ident'>f32</span> <span class='op'>=</span> <span class='ident'>Num</span>::<span class='ident'>from_str_radix</span>(<span class='string'>"0.0"</span>, <span class='number'>10</span>).<span class='ident'>unwrap</span>();
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>f</span>, <span class='number'>0.0</span>);
}
</pre>
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