1 files changed, 69 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/parsing/lexer/numbers.rs b/crates/ra_syntax/src/parsing/lexer/numbers.rs
new file mode 100644
index 000000000..7f6abe1d5
--- /dev/null
+++ b/crates/ra_syntax/src/parsing/lexer/numbers.rs
@@ -0,0 +1,69 @@
+use crate::parsing::lexer::{
+    ptr::Ptr,
+    classes::*,
+};
+
+use crate::SyntaxKind::{self, *};
+
+pub(crate) fn scan_number(c: char, ptr: &mut Ptr) -> SyntaxKind {
+    if c == '0' {
+        match ptr.current().unwrap_or('\0') {
+            'b' | 'o' => {
+                ptr.bump();
+                scan_digits(ptr, false);
+            }
+            'x' => {
+                ptr.bump();
+                scan_digits(ptr, true);
+            }
+            '0'...'9' | '_' | '.' | 'e' | 'E' => {
+                scan_digits(ptr, true);
+            }
+            _ => return INT_NUMBER,
+        }
+    } else {
+        scan_digits(ptr, false);
+    }
+
+    // might be a float, but don't be greedy if this is actually an
+    // integer literal followed by field/method access or a range pattern
+    // (`0..2` and `12.foo()`)
+    if ptr.at('.') && !(ptr.at_str("..") || ptr.nth_is_p(1, is_ident_start)) {
+        // might have stuff after the ., and if it does, it needs to start
+        // with a number
+        ptr.bump();
+        scan_digits(ptr, false);
+        scan_float_exponent(ptr);
+        return FLOAT_NUMBER;
+    }
+    // it might be a float if it has an exponent
+    if ptr.at('e') || ptr.at('E') {
+        scan_float_exponent(ptr);
+        return FLOAT_NUMBER;
+    }
+    INT_NUMBER
+}
+
+fn scan_digits(ptr: &mut Ptr, allow_hex: bool) {
+    while let Some(c) = ptr.current() {
+        match c {
+            '_' | '0'...'9' => {
+                ptr.bump();
+            }
+            'a'...'f' | 'A'...'F' if allow_hex => {
+                ptr.bump();
+            }
+            _ => return,
+        }
+    }
+}
+
+fn scan_float_exponent(ptr: &mut Ptr) {
+    if ptr.at('e') || ptr.at('E') {
+        ptr.bump();
+        if ptr.at('-') || ptr.at('+') {
+            ptr.bump();
+        }
+        scan_digits(ptr, false);
+    }
+}