chore: simplify codec checks code (#102)

Signed-off-by: tison <wander4096@gmail.com>

Author: tisonkun

datasketches/src/bloom/mod.rs

@@ -30,7 +30,7 @@
 //!
 //! # Usage
 //!
-//! ```rust
+//! ```
 //! use datasketches::bloom::BloomFilter;
 //! use datasketches::bloom::BloomFilterBuilder;
 //!
@@ -60,7 +60,7 @@
 //!
 //! Automatically calculates optimal size and hash functions:
 //!
-//! ```rust
+//! ```
 //! # use datasketches::bloom::BloomFilterBuilder;
 //! let filter = BloomFilterBuilder::with_accuracy(
 //!     10_000, // Expected max items
@@ -74,7 +74,7 @@
 //!
 //! Specify requested bit count and hash functions (rounded up to a multiple of 64 bits):
 //!
-//! ```rust
+//! ```
 //! # use datasketches::bloom::BloomFilterBuilder;
 //! let filter = BloomFilterBuilder::with_size(
 //!     95_851, // Number of bits
@@ -87,7 +87,7 @@
 //!
 //! Bloom filters support efficient set operations:
 //!
-//! ```rust
+//! ```
 //! # use datasketches::bloom::BloomFilterBuilder;
 //! let mut filter1 = BloomFilterBuilder::with_accuracy(100, 0.01).build();
 //! let mut filter2 = BloomFilterBuilder::with_accuracy(100, 0.01).build();

datasketches/src/bloom/sketch.rs

@@ -20,9 +20,10 @@ use std::hash::Hasher;
 
 use crate::codec::SketchBytes;
 use crate::codec::SketchSlice;
+use crate::codec::assert::ensure_preamble_longs_in_range;
+use crate::codec::assert::ensure_serial_version_is;
+use crate::codec::assert::insufficient_data;
 use crate::codec::family::Family;
-use crate::codec::utility::ensure_preamble_longs_in_range;
-use crate::codec::utility::ensure_serial_version_is;
 use crate::error::Error;
 use crate::hash::XxHash64;
 
@@ -399,18 +400,14 @@ impl BloomFilter {
         // Read preamble
         let preamble_longs = cursor
             .read_u8()
-            .map_err(|_| Error::insufficient_data("preamble_longs"))?;
+            .map_err(insufficient_data("preamble_longs"))?;
         let serial_version = cursor
             .read_u8()
-            .map_err(|_| Error::insufficient_data("serial_version"))?;
-        let family_id = cursor
-            .read_u8()
-            .map_err(|_| Error::insufficient_data("family_id"))?;
+            .map_err(insufficient_data("serial_version"))?;
+        let family_id = cursor.read_u8().map_err(insufficient_data("family_id"))?;
 
         // Byte 3: flags byte (directly after family_id)
-        let flags = cursor
-            .read_u8()
-            .map_err(|_| Error::insufficient_data("flags"))?;
+        let flags = cursor.read_u8().map_err(insufficient_data("flags"))?;
 
         // Validate
         Family::BLOOMFILTER.validate_id(family_id)?;
@@ -425,7 +422,7 @@ impl BloomFilter {
         // Bytes 4-5: num_hashes (u16)
         let num_hashes = cursor
             .read_u16_le()
-            .map_err(|_| Error::insufficient_data("num_hashes"))?;
+            .map_err(insufficient_data("num_hashes"))?;
         if num_hashes == 0 || num_hashes > i16::MAX as u16 {
             return Err(Error::deserial(format!(
                 "invalid num_hashes: expected [1, {}], got {}",
@@ -436,18 +433,14 @@ impl BloomFilter {
         // Bytes 6-7: unused (u16)
         let _unused = cursor
             .read_u16_le()
-            .map_err(|_| Error::insufficient_data("unused_header"))?;
-        let seed = cursor
-            .read_u64_le()
-            .map_err(|_| Error::insufficient_data("seed"))?;
+            .map_err(insufficient_data("unused_header"))?;
+        let seed = cursor.read_u64_le().map_err(insufficient_data("seed"))?;
 
         // Bit array capacity is stored as number of 64-bit words (int32) + unused padding (uint32).
         let num_longs = cursor
             .read_i32_le()
-            .map_err(|_| Error::insufficient_data("num_longs"))?;
-        let _unused = cursor
-            .read_u32_le()
-            .map_err(|_| Error::insufficient_data("unused"))?;
+            .map_err(insufficient_data("num_longs"))?;
+        let _unused = cursor.read_u32_le().map_err(insufficient_data("unused"))?;
 
         if num_longs <= 0 {
             return Err(Error::deserial(format!(
@@ -465,12 +458,12 @@ impl BloomFilter {
         } else {
             let raw_num_bits_set = cursor
                 .read_u64_le()
-                .map_err(|_| Error::insufficient_data("num_bits_set"))?;
+                .map_err(insufficient_data("num_bits_set"))?;
 
             for word in &mut bit_array {
                 *word = cursor
                     .read_u64_le()
-                    .map_err(|_| Error::insufficient_data("bit_array"))?;
+                    .map_err(insufficient_data("bit_array"))?;
             }
 
             // Handle "dirty" state: 0xFFFFFFFFFFFFFFFF indicates bits need recounting

datasketches/src/codec/utility.rs datasketches/src/codec/assert.rsdatasketches/src/codec/utility.rs renamed to datasketches/src/codec/assert.rs

@@ -20,6 +20,10 @@ use std::ops::RangeBounds;
 
 use crate::error::Error;
 
+pub(crate) fn insufficient_data(tag: &'static str) -> impl FnOnce(std::io::Error) -> Error {
+    move |_| Error::insufficient_data(tag)
+}
+
 pub(crate) fn ensure_serial_version_is(expected: u8, actual: u8) -> Result<(), Error> {
     if expected == actual {
         Ok(())

datasketches/src/codec/mod.rs

@@ -24,5 +24,5 @@ pub use self::decode::SketchSlice;
 pub use self::encode::SketchBytes;
 
 // private to datasketches crate
+pub(crate) mod assert;
 pub(crate) mod family;
-pub(crate) mod utility;

datasketches/src/countmin/mod.rs

@@ -22,7 +22,7 @@
 //!
 //! # Usage
 //!
-//! ```rust
+//! ```
 //! # use datasketches::countmin::CountMinSketch;
 //! let mut sketch = CountMinSketch::<i64>::new(5, 256);
 //! sketch.update("apple");
@@ -32,7 +32,7 @@
 //!
 //! # Configuration Helpers
 //!
-//! ```rust
+//! ```
 //! # use datasketches::countmin::CountMinSketch;
 //! let buckets = CountMinSketch::<i64>::suggest_num_buckets(0.01);
 //! let hashes = CountMinSketch::<i64>::suggest_num_hashes(0.99);

datasketches/src/countmin/sketch.rs

@@ -20,9 +20,10 @@ use std::hash::Hasher;
 
 use crate::codec::SketchBytes;
 use crate::codec::SketchSlice;
+use crate::codec::assert::ensure_preamble_longs_in;
+use crate::codec::assert::ensure_serial_version_is;
+use crate::codec::assert::insufficient_data;
 use crate::codec::family::Family;
-use crate::codec::utility::ensure_preamble_longs_in;
-use crate::codec::utility::ensure_serial_version_is;
 use crate::countmin::CountMinValue;
 use crate::countmin::UnsignedCountMinValue;
 use crate::countmin::serialization::FLAGS_IS_EMPTY;
@@ -61,7 +62,7 @@ impl<T: CountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// let sketch = CountMinSketch::<i64>::new(4, 128);
     /// assert_eq!(sketch.num_buckets(), 128);
@@ -82,7 +83,7 @@ impl<T: CountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// let sketch = CountMinSketch::<i64>::with_seed(4, 64, 42);
     /// assert_eq!(sketch.seed(), 42);
@@ -153,7 +154,7 @@ impl<T: CountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// let mut sketch = CountMinSketch::<i64>::new(4, 128);
     /// sketch.update("apple");
@@ -167,7 +168,7 @@ impl<T: CountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// let mut sketch = CountMinSketch::<i64>::new(4, 128);
     /// sketch.update_with_weight("banana", 3);
@@ -191,7 +192,7 @@ impl<T: CountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// let mut sketch = CountMinSketch::<i64>::new(4, 128);
     /// sketch.update_with_weight("pear", 2);
@@ -231,7 +232,7 @@ impl<T: CountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// let mut left = CountMinSketch::<i64>::new(4, 128);
     /// let mut right = CountMinSketch::<i64>::new(4, 128);
@@ -261,7 +262,7 @@ impl<T: CountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// # let mut sketch = CountMinSketch::<i64>::new(4, 128);
     /// # sketch.update("apple");
@@ -306,7 +307,7 @@ impl<T: CountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// # let mut sketch = CountMinSketch::<i64>::new(4, 64);
     /// # sketch.update("apple");
@@ -322,7 +323,7 @@ impl<T: CountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// # let mut sketch = CountMinSketch::<i64>::with_seed(4, 64, 7);
     /// # sketch.update("apple");
@@ -331,34 +332,40 @@ impl<T: CountMinValue> CountMinSketch<T> {
     /// assert!(decoded.estimate("apple") >= 1);
     /// ```
     pub fn deserialize_with_seed(bytes: &[u8], seed: u64) -> Result<Self, Error> {
-        fn make_error(tag: &'static str) -> impl FnOnce(std::io::Error) -> Error {
-            move |_| Error::insufficient_data(tag)
-        }
-
         fn read_value<T: CountMinValue>(
             cursor: &mut SketchSlice<'_>,
             tag: &'static str,
         ) -> Result<T, Error> {
             let mut bs = [0u8; 8];
-            cursor.read_exact(&mut bs).map_err(make_error(tag))?;
+            cursor.read_exact(&mut bs).map_err(insufficient_data(tag))?;
             T::try_from_bytes(bs)
         }
 
         let mut cursor = SketchSlice::new(bytes);
-        let preamble_longs = cursor.read_u8().map_err(make_error("preamble_longs"))?;
-        let serial_version = cursor.read_u8().map_err(make_error("serial_version"))?;
-        let family_id = cursor.read_u8().map_err(make_error("family_id"))?;
-        let flags = cursor.read_u8().map_err(make_error("flags"))?;
-        cursor.read_u32_le().map_err(make_error("<unused>"))?;
+        let preamble_longs = cursor
+            .read_u8()
+            .map_err(insufficient_data("preamble_longs"))?;
+        let serial_version = cursor
+            .read_u8()
+            .map_err(insufficient_data("serial_version"))?;
+        let family_id = cursor.read_u8().map_err(insufficient_data("family_id"))?;
+        let flags = cursor.read_u8().map_err(insufficient_data("flags"))?;
+        cursor
+            .read_u32_le()
+            .map_err(insufficient_data("<unused>"))?;
 
         Family::COUNTMIN.validate_id(family_id)?;
         ensure_serial_version_is(SERIAL_VERSION, serial_version)?;
         ensure_preamble_longs_in(&[PREAMBLE_LONGS_SHORT], preamble_longs)?;
 
-        let num_buckets = cursor.read_u32_le().map_err(make_error("num_buckets"))?;
-        let num_hashes = cursor.read_u8().map_err(make_error("num_hashes"))?;
-        let seed_hash = cursor.read_u16_le().map_err(make_error("seed_hash"))?;
-        cursor.read_u8().map_err(make_error("unused8"))?;
+        let num_buckets = cursor
+            .read_u32_le()
+            .map_err(insufficient_data("num_buckets"))?;
+        let num_hashes = cursor.read_u8().map_err(insufficient_data("num_hashes"))?;
+        let seed_hash = cursor
+            .read_u16_le()
+            .map_err(insufficient_data("seed_hash"))?;
+        cursor.read_u8().map_err(insufficient_data("unused8"))?;
 
         let expected_seed_hash = compute_seed_hash(seed);
         if seed_hash != expected_seed_hash {
@@ -410,7 +417,7 @@ impl<T: UnsignedCountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// let mut sketch = CountMinSketch::<u64>::new(4, 128);
     /// sketch.update_with_weight("apple", 3);
@@ -431,7 +438,7 @@ impl<T: UnsignedCountMinValue> CountMinSketch<T> {
     ///
     /// # Examples
     ///
-    /// ```rust
+    /// ```
     /// # use datasketches::countmin::CountMinSketch;
     /// let mut sketch = CountMinSketch::<u64>::new(4, 128);
     /// sketch.update_with_weight("apple", 3);