rust: convert pgsql to nom 8

Provide Nom 8 variants for some of our common parser functions, which
can become the defaults after a complete Nom 8 conversion.

Author: jasonish

rust/src/common.rs

@@ -62,6 +62,46 @@ pub mod nom7 {
     }
 }
 
+pub mod nom8 {
+    use nom8::bytes::streaming::{tag, take_until};
+    use nom8::error::{Error, ParseError};
+    use nom8::ErrorConvert;
+    use nom8::{IResult, Parser};
+
+    /// Reimplementation of `take_until_and_consume` for nom 8
+    ///
+    /// `take_until` does not consume the matched tag, and
+    /// `take_until_and_consume` was removed in nom 7. This function
+    /// provides an implementation (specialized for `&[u8]`).
+    pub fn take_until_and_consume<'a, E: ParseError<&'a [u8]>>(
+        t: &'a [u8],
+    ) -> impl FnMut(&'a [u8]) -> IResult<&'a [u8], &'a [u8], E> {
+        move |i: &'a [u8]| {
+            let (i, res) = take_until(t).parse(i)?;
+            let (i, _) = tag(t).parse(i)?;
+            Ok((i, res))
+        }
+    }
+
+    /// Specialized version of the nom 8 `bits` combinator
+    ///
+    /// The `bits combinator has trouble inferring the transient error type
+    /// used by the tuple parser, because the function is generic and any
+    /// error type would be valid.
+    /// Use an explicit error type (as described in
+    /// https://docs.rs/nom/7.1.0/nom/bits/fn.bits.html) to solve this problem, and
+    /// specialize this function for `&[u8]`.
+    pub fn bits<'a, O, E, P>(parser: P) -> impl FnMut(&'a [u8]) -> IResult<&'a [u8], O, E>
+    where
+        E: ParseError<&'a [u8]>,
+        Error<(&'a [u8], usize)>: ErrorConvert<E>,
+        P: FnMut((&'a [u8], usize)) -> IResult<(&'a [u8], usize), O, Error<(&'a [u8], usize)>>,
+    {
+        // use full path to disambiguate nom `bits` from this current function name
+        nom8::bits::bits(parser)
+    }
+}
+
 /// Convert a String to C-compatible string
 ///
 /// This function will consume the provided data and use the underlying bytes to construct a new