Adds lazy reader support for blobs (#629)

Author: zslayton

src/lazy/binary/raw/value.rs

@@ -406,7 +406,7 @@ impl<'data> LazyRawBinaryValue<'data> {
     fn read_blob(&self) -> ValueParseResult<'data, BinaryEncoding> {
         debug_assert!(self.encoded_value.ion_type() == IonType::Blob);
         let bytes = self.value_body()?;
-        Ok(RawValueRef::Blob(bytes))
+        Ok(RawValueRef::Blob(bytes.into()))
     }
 
     /// Helper method called by [`Self::read`]. Reads the current value as a clob.

src/lazy/bytes_ref.rs

@@ -0,0 +1,123 @@
+use crate::text::text_formatter::IonValueFormatter;
+use crate::Bytes;
+use std::borrow::Cow;
+use std::fmt::{Debug, Display, Formatter};
+use std::ops::Deref;
+
+pub struct BytesRef<'data> {
+    data: Cow<'data, [u8]>,
+}
+
+impl<'data> Deref for BytesRef<'data> {
+    type Target = [u8];
+
+    fn deref(&self) -> &Self::Target {
+        self.data.as_ref()
+    }
+}
+
+impl<'data> BytesRef<'data> {
+    pub fn to_owned(&self) -> Bytes {
+        Bytes::from(self.as_ref())
+    }
+
+    pub fn into_owned(self) -> Bytes {
+        Bytes::from(self)
+    }
+
+    pub fn data(&self) -> &[u8] {
+        self.as_ref()
+    }
+}
+
+impl<'data> From<BytesRef<'data>> for Bytes {
+    fn from(value: BytesRef<'data>) -> Self {
+        match value.data {
+            Cow::Borrowed(bytes) => Bytes::from(bytes),
+            Cow::Owned(bytes) => Bytes::from(bytes),
+        }
+    }
+}
+
+impl<'data, const N: usize> From<&'data [u8; N]> for BytesRef<'data> {
+    fn from(bytes: &'data [u8; N]) -> Self {
+        BytesRef {
+            data: Cow::from(bytes.as_ref()),
+        }
+    }
+}
+
+impl<'data> From<&'data [u8]> for BytesRef<'data> {
+    fn from(bytes: &'data [u8]) -> Self {
+        BytesRef {
+            data: Cow::from(bytes),
+        }
+    }
+}
+
+impl<'data> From<Vec<u8>> for BytesRef<'data> {
+    fn from(bytes: Vec<u8>) -> Self {
+        BytesRef {
+            data: Cow::from(bytes),
+        }
+    }
+}
+
+impl<'data> From<&'data str> for BytesRef<'data> {
+    fn from(text: &'data str) -> Self {
+        BytesRef {
+            data: Cow::from(text.as_bytes()),
+        }
+    }
+}
+
+impl<'data> PartialEq<[u8]> for BytesRef<'data> {
+    fn eq(&self, other: &[u8]) -> bool {
+        self.data() == other
+    }
+}
+
+impl<'data> PartialEq<&[u8]> for BytesRef<'data> {
+    fn eq(&self, other: &&[u8]) -> bool {
+        self.data() == *other
+    }
+}
+
+impl<'data> PartialEq<BytesRef<'data>> for [u8] {
+    fn eq(&self, other: &BytesRef<'data>) -> bool {
+        self == other.data()
+    }
+}
+
+impl<'a, 'b> PartialEq<BytesRef<'a>> for BytesRef<'b> {
+    fn eq(&self, other: &BytesRef<'a>) -> bool {
+        self == other.data()
+    }
+}
+
+impl<'data> Display for BytesRef<'data> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        let mut formatter = IonValueFormatter { output: f };
+        formatter
+            .format_blob(self.data())
+            .map_err(|_| std::fmt::Error)
+    }
+}
+
+impl<'data> Debug for BytesRef<'data> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        const NUM_BYTES_TO_SHOW: usize = 32;
+        let data = self.data.as_ref();
+        // Shows up to the first 32 bytes in hex
+        write!(f, "BytesRef: [")?;
+        for byte in data.iter().copied().take(NUM_BYTES_TO_SHOW) {
+            write!(f, "{:x} ", byte)?;
+        }
+        if data.len() > NUM_BYTES_TO_SHOW {
+            write!(f, "...{} more", (data.len() - NUM_BYTES_TO_SHOW))?;
+        }
+        write!(f, "]")?;
+
+        Ok(())
+    }
+}

src/lazy/mod.rs

@@ -1,8 +1,9 @@
 //! Provides an ergonomic, lazy view of an Ion stream that permits random access within each
 //! top level value.
 
-mod any_encoding;
+pub mod any_encoding;
 pub mod binary;
+pub mod bytes_ref;
 pub mod decoder;
 pub(crate) mod encoding;
 pub mod raw_stream_item;

src/lazy/raw_value_ref.rs

@@ -1,3 +1,4 @@
+use crate::lazy::bytes_ref::BytesRef;
 use crate::lazy::decoder::LazyDecoder;
 use crate::lazy::str_ref::StrRef;
 use crate::result::IonFailure;
@@ -18,7 +19,7 @@ pub enum RawValueRef<'data, D: LazyDecoder<'data>> {
     Timestamp(Timestamp),
     String(StrRef<'data>),
     Symbol(RawSymbolTokenRef<'data>),
-    Blob(&'data [u8]),
+    Blob(BytesRef<'data>),
     Clob(&'data [u8]),
     SExp(D::SExp),
     List(D::List),
@@ -140,7 +141,7 @@ impl<'data, D: LazyDecoder<'data>> RawValueRef<'data, D> {
         }
     }
 
-    pub fn expect_blob(self) -> IonResult<&'data [u8]> {
+    pub fn expect_blob(self) -> IonResult<BytesRef<'data>> {
         if let RawValueRef::Blob(b) = self {
             Ok(b)
         } else {
@@ -247,7 +248,7 @@ mod tests {
         );
         assert_eq!(
             reader.next()?.expect_value()?.read()?.expect_blob()?,
-            &[0x06, 0x5A, 0x1B] // Base64-decoded "Blob"
+            [0x06u8, 0x5A, 0x1B].as_ref() // Base64-decoded "Blob"
         );
         assert_eq!(
             reader.next()?.expect_value()?.read()?.expect_clob()?,

src/lazy/text/buffer.rs

@@ -6,7 +6,7 @@ use std::str::FromStr;
 
 use nom::branch::alt;
 use nom::bytes::streaming::{is_a, is_not, tag, take_until, take_while1, take_while_m_n};
-use nom::character::streaming::{char, digit1, one_of, satisfy};
+use nom::character::streaming::{alphanumeric1, char, digit1, one_of, satisfy};
 use nom::combinator::{consumed, fail, map, not, opt, peek, recognize, success, value};
 use nom::error::{ErrorKind, ParseError};
 use nom::multi::{many0_count, many1_count};
@@ -17,8 +17,8 @@ use crate::lazy::encoding::TextEncoding;
 use crate::lazy::raw_stream_item::RawStreamItem;
 use crate::lazy::text::encoded_value::EncodedTextValue;
 use crate::lazy::text::matched::{
-    MatchedDecimal, MatchedFloat, MatchedHoursAndMinutes, MatchedInt, MatchedString, MatchedSymbol,
-    MatchedTimestamp, MatchedTimestampOffset, MatchedValue,
+    MatchedBlob, MatchedDecimal, MatchedFloat, MatchedHoursAndMinutes, MatchedInt, MatchedString,
+    MatchedSymbol, MatchedTimestamp, MatchedTimestampOffset, MatchedValue,
 };
 use crate::lazy::text::parse_result::{InvalidInputError, IonParseError};
 use crate::lazy::text::parse_result::{IonMatchResult, IonParseResult};
@@ -497,6 +497,12 @@ impl<'data> TextBufferView<'data> {
                     )
                 },
             ),
+            map(
+                match_and_length(Self::match_blob),
+                |(matched_blob, length)| {
+                    EncodedTextValue::new(MatchedValue::Blob(matched_blob), self.offset(), length)
+                },
+            ),
             map(
                 match_and_length(Self::match_list),
                 |(matched_list, length)| {
@@ -1341,6 +1347,36 @@ impl<'data> TextBufferView<'data> {
             recognize(pair(one_of("012345"), Self::match_any_digit)),
         )(self)
     }
+
+    /// Matches a complete blob, including the opening `{{` and closing `}}`.
+    pub fn match_blob(self) -> IonParseResult<'data, MatchedBlob> {
+        delimited(
+            tag("{{"),
+            // Only whitespace (not comments) can appear within the blob
+            recognize(Self::match_base64_content),
+            preceded(Self::match_optional_whitespace, tag("}}")),
+        )
+        .map(|base64_data| {
+            MatchedBlob::new(base64_data.offset() - self.offset(), base64_data.len())
+        })
+        .parse(self)
+    }
+
+    /// Matches the base64 content within a blob. Ion allows the base64 content to be broken up with
+    /// whitespace, so the matched input region may need to be stripped of whitespace before
+    /// the data can be decoded.
+    fn match_base64_content(self) -> IonMatchResult<'data> {
+        recognize(terminated(
+            many0_count(preceded(
+                Self::match_optional_whitespace,
+                alt((alphanumeric1, is_a("+/"))),
+            )),
+            opt(preceded(
+                Self::match_optional_whitespace,
+                alt((tag("=="), tag("="))),
+            )),
+        ))(self)
+    }
 }
 
 // === nom trait implementations ===
@@ -2008,4 +2044,59 @@ mod tests {
             mismatch_sexp(input);
         }
     }
+
+    #[test]
+    fn test_match_blob() {
+        fn match_blob(input: &str) {
+            MatchTest::new(input).expect_match(match_length(TextBufferView::match_blob));
+        }
+        fn mismatch_blob(input: &str) {
+            MatchTest::new(input).expect_mismatch(match_length(TextBufferView::match_blob));
+        }
+        // Base64 encodings of utf-8 strings
+        let good_inputs = &[
+            // <empty blobs>
+            "{{}}",
+            "{{    }}",
+            "{{\n\t}}",
+            // hello
+            "{{aGVsbG8=}}",
+            "{{  aGVsbG8=}}",
+            "{{aGVsbG8=  }}",
+            "{{\taGVsbG8=\n\n}}",
+            "{{aG  Vs  bG   8 =}}",
+            r#"{{
+                aG Vs  
+                bG 8=
+            }}"#,
+            // hello!
+            "{{aGVsbG8h}}",
+            "{{  aGVsbG8h}}",
+            "{{aGVsbG8h  }}",
+            "{{  aGVsbG8h  }}",
+            // razzle dazzle root beer
+            "{{cmF6emxlIGRhenpsZSByb290IGJlZXI=}}",
+            "{{\ncmF6emxlIGRhenpsZSByb290IGJlZXI=\r}}",
+        ];
+        for input in good_inputs {
+            match_blob(input);
+        }
+
+        let bad_inputs = &[
+            // illegal character $
+            "{{$aGVsbG8=}}",
+            // comment within braces
+            r#"{{
+                // Here's the data:
+                aGVsbG8=
+            }}"#,
+            // padding at the beginning
+            "{{=aGVsbG8}}",
+            // too much padding
+            "{{aGVsbG8===}}",
+        ];
+        for input in bad_inputs {
+            mismatch_blob(input);
+        }
+    }
 }

src/lazy/text/encoded_value.rs

@@ -130,6 +130,7 @@ impl EncodedTextValue {
             MatchedValue::Timestamp(_) => IonType::Timestamp,
             MatchedValue::String(_) => IonType::String,
             MatchedValue::Symbol(_) => IonType::Symbol,
+            MatchedValue::Blob(_) => IonType::Blob,
             MatchedValue::List => IonType::List,
             MatchedValue::SExp => IonType::SExp,
             MatchedValue::Struct => IonType::Struct,