Merge branch 'tune_to_float' into 'master'

Optimize numeric to floating-point.

See merge request codbase/pgnumeric!1

Cargo.toml

@@ -19,6 +19,7 @@ big-endian-varlen=[]
 lazy_static = "1.4"
 smallvec = "1.3"
 cfg-if = "0.1"
+strtod = "0.0.1"
 
 [dev-dependencies]
 criterion = "^0.3"

benches/benchmark.rs

@@ -109,7 +109,7 @@ fn into_benchmark(c: &mut Criterion) {
     c.bench_function("to_f64", |b| {
         let val = parse("1.234567890123456789e10");
         b.iter(|| {
-            let _n: f32 = into(black_box(&val));
+            let _n: f64 = into(black_box(&val));
         })
     });
 }

src/convert.rs

@@ -625,11 +625,23 @@ impl<'a> TryFrom<&NumericVar<'a>> for f32 {
     #[inline]
     fn try_from(value: &NumericVar<'a>) -> Result<Self, Self::Error> {
         use std::fmt::Write;
+        if value.is_nan() {
+            return Ok(std::f32::NAN);
+        }
         let mut buf = String::with_capacity(32);
         buf.write_fmt(format_args!("{}", value))
             .expect("returned an error unexpectedly");
-        let f = buf.parse::<f32>()?;
-        Ok(f)
+
+        match strtod::strtod(&buf) {
+            Some(val) => {
+                let f = val as f32;
+                if (f.is_infinite() && !val.is_infinite()) || (f == 0.0 && val != 0.0) {
+                    return Err(NumericTryFromError::overflow());
+                }
+                Ok(f)
+            }
+            None => Err(NumericTryFromError::overflow()),
+        }
     }
 }
 
@@ -639,11 +651,17 @@ impl<'a> TryFrom<&NumericVar<'a>> for f64 {
     #[inline]
     fn try_from(value: &NumericVar<'a>) -> Result<Self, Self::Error> {
         use std::fmt::Write;
+        if value.is_nan() {
+            return Ok(std::f64::NAN);
+        }
         let mut buf = String::with_capacity(32);
         buf.write_fmt(format_args!("{}", value))
             .expect("returned an error unexpectedly");
-        let f = buf.parse::<f64>()?;
-        Ok(f)
+
+        match strtod::strtod(&buf) {
+            Some(f) => Ok(f),
+            None => Err(NumericTryFromError::overflow()),
+        }
     }
 }
 
@@ -1140,7 +1158,7 @@ mod tests {
         assert_try_into("1.23456789e-10", 1.23456789e-10f32);
         assert_try_into("3.40282347e+38", std::f32::MAX);
         assert_try_into("-3.40282347e+38", std::f32::MIN);
-        assert_try_into("1e39", std::f32::INFINITY);
+        assert_try_into_overflow::<f32>("1e39");
         assert_try_into("1.17549435e-38", std::f32::MIN_POSITIVE);
         assert!(try_into::<&str, f32>("NaN").is_nan());
     }

src/var.rs

@@ -2102,17 +2102,17 @@ impl<'a> NumericVar<'a> {
     /// `self` is displayed to the number of digits indicated by its dscale.
     pub fn write<W: fmt::Write>(&self, f: &mut W) -> Result<(), fmt::Error> {
         if self.is_nan() {
-            return write!(f, "NaN");
+            return f.write_str("NaN");
         }
 
         // Output a dash for negative values.
         if self.sign == NUMERIC_NEG {
-            write!(f, "-")?;
+            f.write_char('-')?;
         }
 
         // Output all digits before the decimal point.
         if self.weight < 0 {
-            write!(f, "0")?;
+            f.write_char('0')?;
         } else {
             let digits = self.digits();
             debug_assert_eq!(digits.len(), self.ndigits as usize);
@@ -2137,7 +2137,7 @@ impl<'a> NumericVar<'a> {
 
         // If requested, output a decimal point and all the digits that follow it.
         if self.dscale > 0 {
-            write!(f, ".")?;
+            f.write_char('.')?;
 
             let digits = self.digits();
             debug_assert_eq!(digits.len(), self.ndigits as usize);