Move runtime support to its own module

1 files changed, 122 insertions, 0 deletions

diff --git a/src/runtime.rs b/src/runtime.rs
new file mode 100644
index 0000000..6ebd1f8
--- /dev/null
+++ b/src/runtime.rs
@@ -0,0 +1,122 @@
+use ext::TokenStreamExt;
+pub use proc_macro2::*;
+
+fn is_ident_start(c: u8) -> bool {
+    (b'a' <= c && c <= b'z') || (b'A' <= c && c <= b'Z') || c == b'_'
+}
+
+fn is_ident_continue(c: u8) -> bool {
+    (b'a' <= c && c <= b'z')
+        || (b'A' <= c && c <= b'Z')
+        || c == b'_'
+        || (b'0' <= c && c <= b'9')
+}
+
+fn is_ident(token: &str) -> bool {
+    if token.bytes().all(|digit| digit >= b'0' && digit <= b'9') {
+        return false;
+    }
+
+    let mut bytes = token.bytes();
+    let first = bytes.next().unwrap();
+    if !is_ident_start(first) {
+        return false;
+    }
+    for ch in bytes {
+        if !is_ident_continue(ch) {
+            return false;
+        }
+    }
+    true
+}
+
+pub fn parse(tokens: &mut TokenStream, span: Span, s: &str) {
+    if is_ident(s) {
+        // Fast path, since idents are the most common token.
+        tokens.append(Ident::new(s, span));
+    } else {
+        let s: TokenStream = s.parse().expect("invalid token stream");
+        tokens.extend(s.into_iter().map(|mut t| {
+            t.set_span(span);
+            t
+        }));
+    }
+}
+
+macro_rules! push_punct {
+    ($name:ident $char1:tt) => {
+        pub fn $name(tokens: &mut TokenStream, span: Span) {
+            let mut punct = Punct::new($char1, Spacing::Alone);
+            punct.set_span(span);
+            tokens.append(punct);
+        }
+    };
+    ($name:ident $char1:tt $char2:tt) => {
+        pub fn $name(tokens: &mut TokenStream, span: Span) {
+            let mut punct = Punct::new($char1, Spacing::Joint);
+            punct.set_span(span);
+            tokens.append(punct);
+            let mut punct = Punct::new($char2, Spacing::Alone);
+            punct.set_span(span);
+            tokens.append(punct);
+        }
+    };
+    ($name:ident $char1:tt $char2:tt $char3:tt) => {
+        pub fn $name(tokens: &mut TokenStream, span: Span) {
+            let mut punct = Punct::new($char1, Spacing::Joint);
+            punct.set_span(span);
+            tokens.append(punct);
+            let mut punct = Punct::new($char2, Spacing::Joint);
+            punct.set_span(span);
+            tokens.append(punct);
+            let mut punct = Punct::new($char3, Spacing::Alone);
+            punct.set_span(span);
+            tokens.append(punct);
+        }
+    };
+}
+
+push_punct!(push_add '+');
+push_punct!(push_add_eq '+' '=');
+push_punct!(push_and '&');
+push_punct!(push_and_and '&' '&');
+push_punct!(push_and_eq '&' '=');
+push_punct!(push_at '@');
+push_punct!(push_bang '!');
+push_punct!(push_caret '^');
+push_punct!(push_caret_eq '^' '=');
+push_punct!(push_colon ':');
+push_punct!(push_colon2 ':' ':');
+push_punct!(push_comma ',');
+push_punct!(push_div '/');
+push_punct!(push_div_eq '/' '=');
+push_punct!(push_dot '.');
+push_punct!(push_dot2 '.' '.');
+push_punct!(push_dot3 '.' '.' '.');
+push_punct!(push_dot_dot_eq '.' '.' '=');
+push_punct!(push_eq '=');
+push_punct!(push_eq_eq '=' '=');
+push_punct!(push_ge '>' '=');
+push_punct!(push_gt '>');
+push_punct!(push_le '<' '=');
+push_punct!(push_lt '<');
+push_punct!(push_mul_eq '*' '=');
+push_punct!(push_ne '!' '=');
+push_punct!(push_or '|');
+push_punct!(push_or_eq '|' '=');
+push_punct!(push_or_or '|' '|');
+push_punct!(push_pound '#');
+push_punct!(push_question '?');
+push_punct!(push_rarrow '-' '>');
+push_punct!(push_larrow '<' '-');
+push_punct!(push_rem '%');
+push_punct!(push_rem_eq '%' '=');
+push_punct!(push_fat_arrow '=' '>');
+push_punct!(push_semi ';');
+push_punct!(push_shl '<' '<');
+push_punct!(push_shl_eq '<' '<' '=');
+push_punct!(push_shr '>' '>');
+push_punct!(push_shr_eq '>' '>' '=');
+push_punct!(push_star '*');
+push_punct!(push_sub '-');
+push_punct!(push_sub_eq '-' '=');