Add better support for rust-like number literals (#908)

Signed-off-by: max <gmx.sht@gmail.com>

3 files changed, 99 insertions, 5 deletions

diff --git a/askama_parser/src/lib.rs b/askama_parser/src/lib.rs
index ff26483..4d27d70 100644
--- a/askama_parser/src/lib.rs
+++ b/askama_parser/src/lib.rs
@@ -7,11 +7,10 @@ use std::{fmt, str};
 
 use nom::branch::alt;
 use nom::bytes::complete::{escaped, is_not, tag, take_till};
-use nom::character::complete::char;
-use nom::character::complete::{anychar, digit1};
+use nom::character::complete::{anychar, char, one_of, satisfy};
 use nom::combinator::{cut, eof, map, opt, recognize};
 use nom::error::{Error, ErrorKind, FromExternalError};
-use nom::multi::many1;
+use nom::multi::{many0_count, many1};
 use nom::sequence::{delimited, pair, preceded, terminated, tuple};
 use nom::{error_position, AsChar, InputTakeAtPosition};
 
@@ -250,13 +249,74 @@ fn bool_lit(i: &str) -> ParseResult<'_> {
 }
 
 fn num_lit(i: &str) -> ParseResult<'_> {
+    let integer_suffix = |i| {
+        alt((
+            tag("i8"),
+            tag("i16"),
+            tag("i32"),
+            tag("i64"),
+            tag("i128"),
+            tag("isize"),
+            tag("u8"),
+            tag("u16"),
+            tag("u32"),
+            tag("u64"),
+            tag("u128"),
+            tag("usize"),
+        ))(i)
+    };
+    let float_suffix = |i| alt((tag("f32"), tag("f64")))(i);
+
     recognize(tuple((
         opt(char('-')),
-        digit1,
-        opt(pair(char('.'), digit1)),
+        alt((
+            recognize(tuple((
+                char('0'),
+                alt((
+                    recognize(tuple((char('b'), separated_digits(2, false)))),
+                    recognize(tuple((char('o'), separated_digits(8, false)))),
+                    recognize(tuple((char('x'), separated_digits(16, false)))),
+                )),
+                opt(integer_suffix),
+            ))),
+            recognize(tuple((
+                separated_digits(10, true),
+                opt(alt((
+                    integer_suffix,
+                    float_suffix,
+                    recognize(tuple((
+                        opt(tuple((char('.'), separated_digits(10, true)))),
+                        one_of("eE"),
+                        opt(one_of("+-")),
+                        separated_digits(10, false),
+                        opt(float_suffix),
+                    ))),
+                    recognize(tuple((
+                        char('.'),
+                        separated_digits(10, true),
+                        opt(float_suffix),
+                    ))),
+                ))),
+            ))),
+        )),
     )))(i)
 }
 
+/// Underscore separated digits of the given base, unless `start` is true this may start
+/// with an underscore.
+fn separated_digits(radix: u32, start: bool) -> impl Fn(&str) -> ParseResult<'_> {
+    move |i| {
+        recognize(tuple((
+            |i| match start {
+                true => Ok((i, 0)),
+                false => many0_count(char('_'))(i),
+            },
+            satisfy(|ch| ch.is_digit(radix)),
+            many0_count(satisfy(|ch| ch == '_' || ch.is_digit(radix))),
+        )))(i)
+    }
+}
+
 fn str_lit(i: &str) -> ParseResult<'_> {
     let (i, s) = delimited(
         char('"'),
diff --git a/testing/templates/num-literals.html b/testing/templates/num-literals.html
new file mode 100644
index 0000000..90b07db
--- /dev/null
+++ b/testing/templates/num-literals.html
@@ -0,0 +1,11 @@
+{% let plain_int = 9__0__ -%}
+{% let neg_int = -9__0__isize -%}
+{% let suffix_int = 9__0__i32 -%}
+{% let bin_int = 0b__1__0__ -%}
+{% let oct_int = 0o__7__0__ -%}
+{% let hex_int = 0x__f__0__ -%}
+{% let plain_float = 1__0__.5__0__ -%}
+{% let suffix_float = 1__0__.5__0__f32 -%}
+{% let exp_float = 1__0__e+__1__0__f32 -%}
+{% let dotexp_float = 1__0__.5__0__e+__1__0__f32 -%}
+[{{ plain_int }}, {{ neg_int }}, {{ suffix_int }}, {{ bin_int }}, {{ oct_int }}, {{ hex_int }}, {{ plain_float }}, {{ suffix_float }}, {{ exp_float }}, {{ dotexp_float }}]
diff --git a/testing/tests/simple.rs b/testing/tests/simple.rs
index 627a8a3..f0f0a26 100644
--- a/testing/tests/simple.rs
+++ b/testing/tests/simple.rs
@@ -461,3 +461,26 @@ fn test_define_string_var() {
     let template = DefineStringVar;
     assert_eq!(template.render().unwrap(), "");
 }
+
+#[derive(askama::Template)]
+#[template(source = "{% let x = 4.5 %}{{ x }}", ext = "html")]
+struct SimpleFloat;
+
+#[test]
+fn test_simple_float() {
+    let template = SimpleFloat;
+    assert_eq!(template.render().unwrap(), "4.5");
+}
+
+#[derive(askama::Template)]
+#[template(path = "num-literals.html")]
+struct NumLiterals;
+
+#[test]
+fn test_num_literals() {
+    let template = NumLiterals;
+    assert_eq!(
+        template.render().unwrap(),
+        "[90, -90, 90, 2, 56, 240, 10.5, 10.5, 100000000000, 105000000000]",
+    );
+}