Simplify event-id grammar by removing the argument tag.

The tag was meant to disambiguate between arguments and other kinds
of annotations (like event category). However, there are only
arguments at the moment, so the tag is redundant. It can be add back
in later.

Author: michaelwoerister

analyzeme/src/event.rs

@@ -3,9 +3,6 @@ use memchr::memchr;
 use std::borrow::Cow;
 use std::time::Duration;
 
-const SEPARATOR: u8 = 0x1E;
-const ARG_TAG: u8 = 0x11;
-
 #[derive(Clone, Eq, PartialEq, Hash, Debug)]
 pub struct Event<'a> {
     pub event_kind: Cow<'a, str>,
@@ -78,6 +75,8 @@ struct Parser<'a> {
     pos: usize,
 }
 
+const SEPARATOR_BYTE: u8 = measureme::event_id::SEPARATOR_BYTE.as_bytes()[0];
+
 impl<'a> Parser<'a> {
     fn new(full_text: Cow<'a, [u8]>) -> Parser<'a> {
         Parser { full_text, pos: 0 }
@@ -95,7 +94,7 @@ impl<'a> Parser<'a> {
     fn parse_separator_terminated_text(&mut self) -> Result<Cow<'a, str>, String> {
         let start = self.pos;
 
-        let end = memchr(SEPARATOR, &self.full_text[start..])
+        let end = memchr(SEPARATOR_BYTE, &self.full_text[start..])
             .map(|pos| pos + start)
             .unwrap_or(self.full_text.len());
 
@@ -105,27 +104,23 @@ impl<'a> Parser<'a> {
 
         self.pos = end;
 
+        if self.full_text[start .. end].iter().any(u8::is_ascii_control) {
+            return self.err("Found ASCII control character in <text>");
+        }
+
         Ok(self.substring(start, end))
     }
 
     fn parse_arg(&mut self) -> Result<Cow<'a, str>, String> {
-        if self.peek() != SEPARATOR {
+        if self.peek() != SEPARATOR_BYTE {
             return self.err(&format!(
                 "Expected '\\x{:x}' char at start of <argument>",
-                SEPARATOR
+                SEPARATOR_BYTE
             ));
         }
 
         self.pos += 1;
-        let tag = self.peek();
-
-        match tag {
-            ARG_TAG => {
-                self.pos += 1;
-                self.parse_separator_terminated_text()
-            }
-            other => self.err(&format!("Unexpected argument tag '{:x}'", other)),
-        }
+        self.parse_separator_terminated_text()
     }
 
     fn err<T>(&self, message: &str) -> Result<T, String> {
@@ -163,7 +158,7 @@ mod tests {
 
     #[test]
     fn parse_event_id_one_arg() {
-        let (label, args) = Event::parse_event_id(Cow::from("foo\x1e\x11my_arg"));
+        let (label, args) = Event::parse_event_id(Cow::from("foo\x1emy_arg"));
 
         assert_eq!(label, "foo");
         assert_eq!(args, vec![Cow::from("my_arg")]);
@@ -172,7 +167,7 @@ mod tests {
     #[test]
     fn parse_event_id_n_args() {
         let (label, args) =
-            Event::parse_event_id(Cow::from("foo\x1e\x11arg1\x1e\x11arg2\x1e\x11arg3"));
+            Event::parse_event_id(Cow::from("foo\x1earg1\x1earg2\x1earg3"));
 
         assert_eq!(label, "foo");
         assert_eq!(

measureme/src/event_id.rs

@@ -5,14 +5,18 @@ use crate::{Profiler, SerializationSink, StringComponent, StringId};
 /// ```ignore
 ///   <event_id> = <label> {<argument>}
 ///   <label> = <text>
-///   <argument> = '\x1E' '\x11' <text>
-///   <text> = regex([^0x1E]+) // Anything but the separator byte
+///   <argument> = '\x1E' <text>
+///   <text> = regex([^[[:cntrl:]]]+) // Anything but ASCII control characters
 ///  ```
 ///
 /// This means there's always a "label", followed by an optional list of
 /// arguments. Future versions my support other optional suffixes (with a tag
 /// other than '\x11' after the '\x1E' separator), such as a "category".
 
+
+/// The byte used to separate arguments from the label and each other.
+pub const SEPARATOR_BYTE: &str = "\x1E";
+
 pub struct EventIdBuilder<'p, S: SerializationSink> {
     profiler: &'p Profiler<S>,
 }
@@ -32,7 +36,7 @@ impl<'p, S: SerializationSink> EventIdBuilder<'p, S> {
             // Label
             StringComponent::Ref(label),
             // Seperator and start tag for arg
-            StringComponent::Value("\x1E\x11"),
+            StringComponent::Value(SEPARATOR_BYTE),
             // Arg string id
             StringComponent::Ref(arg),
         ])

measureme/src/lib.rs

@@ -37,7 +37,7 @@
 
 #![deny(warnings)]
 
-mod event_id;
+pub mod event_id;
 pub mod file_header;
 #[cfg(any(not(target_arch = "wasm32"), target_os = "wasi"))]
 mod file_serialization_sink;