From 40cd88daee33f4f604b6df93c8bd498c4d8ba1eb Mon Sep 17 00:00:00 2001
From: Caleb Jones <code@calebjones.net>
Date: Thu, 22 Dec 2016 01:43:56 -0500
Subject: [PATCH] Improve the number parser

Instead of redoing all the number extraction ourselves, we now reuse the
number parsing code built into Rust. We simply recognize things that
look like numbers, and pass the string into the appropriate number
parsing function.
---
 src/lib.rs | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 26bd43b..b82be20 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,6 +7,7 @@
 extern crate nom;
 
 use nom::{digit, multispace, IResult};
+use std::str::FromStr;
 
 /// Indicates how parsing failed.
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
@@ -113,11 +114,23 @@ fn valid_ident_char(c: char) -> bool {
 }
 
 named!(number<&str, Sexp>,
-  do_parse!(
-    opt!(multispace) >>
-    integral: digit >>
-    peek!(not!(valid_ident_prefix)) >>
-    (Sexp::Int(integral.chars().fold(0, |i, c| i * 10 + c as i64 - '0' as i64)))
+  preceded!(opt!(multispace),
+    map_res!(
+      recognize!(do_parse!(
+        digit >>
+        is_float: opt!(complete!(tag_s!("."))) >>
+        opt!(complete!(digit)) >>
+        peek!(not!(valid_ident_prefix)) >>
+        ()
+      )),
+      |text: &str| {
+          if text.contains(".") {
+              f64::from_str(text).map(Sexp::Float).or(Err(()))
+          } else {
+              i64::from_str(text).map(Sexp::Int).or(Err(()))
+          }
+      }
+    )
   )
 );
 
@@ -138,6 +151,11 @@ fn test_parse_number() {
     assert_eq!(number("0123456789"), IResult::Done("", Sexp::Int(123456789)));
     assert_eq!(number("    42"), IResult::Done("", Sexp::Int(42)));
 
+    assert_eq!(number("4."), IResult::Done("", Sexp::Float(4.)));
+    assert_eq!(number("4.2"), IResult::Done("", Sexp::Float(4.2)));
+    assert_eq!(number("1.00000000001"),
+               IResult::Done("", Sexp::Float(1.00000000001)));
+
     assert!(number(" 42a").is_err());
     assert_eq!(number("13()"), IResult::Done("()", Sexp::Int(13)));
 
-- 
2.43.2