Add support for i128 and u128

i128 and u128 can now be serialized and deserialized.  Support is
conditionalized on the disabled-by-default `i128` feature flag, and
requires rustc 1.26.0 or later.  The minimum required version of Serde
is now 1.0.60.

Fixes #108

.travis.yml

@@ -8,6 +8,9 @@ matrix:
     - rust: 1.17.0
       script: cargo check
     - rust: 1.21.0
+      script:
+        - cargo build
+        - cargo test
     - rust: nightly
       env: CLIPPY
       script: |
@@ -18,3 +21,4 @@ matrix:
 script:
   - cargo build
   - cargo test
+  - caro test --features "i128"

Cargo.toml

@@ -10,15 +10,19 @@ readme = "README.md"
 keywords = ["yaml", "serde"]
 
 [dependencies]
+cfg-if = "0.1"
 dtoa = "0.4"
 linked-hash-map = "0.5"
-serde = "1.0"
+serde = "1.0.60"
 yaml-rust = "0.4"
 
 [dev-dependencies]
 serde_derive = "1.0"
 unindent = "0.1"
 version-sync = "0.5"
 
+[features]
+i128 = []
+
 [badges]
 travis-ci = { repository = "dtolnay/serde-yaml" }

src/de.rs

@@ -565,9 +565,19 @@ where
     if let Ok(n) = v.parse() {
         return visitor.visit_u64(n);
     }
+    serde_if_integer128! {
+        if let Ok(n) = v.parse() {
+            return visitor.visit_u128(n);
+        }
+    }
     if let Ok(n) = v.parse() {
         return visitor.visit_i64(n);
     }
+    serde_if_integer128! {
+        if let Ok(n) = v.parse() {
+            return visitor.visit_i128(n);
+        }
+    }
     match v.trim_left_matches('+') {
         ".inf" | ".Inf" | ".INF" => return visitor.visit_f64(f64::INFINITY),
         _ => (),
@@ -685,6 +695,23 @@ impl<'de, 'a, 'r> de::Deserializer<'de> for &'r mut Deserializer<'a> {
         self.deserialize_scalar(visitor)
     }
 
+    serde_if_integer128! {
+        #[cfg(feature = "i128")]
+        fn deserialize_i128<V>(self, visitor: V) -> Result<V::Value>
+        where
+            V: Visitor<'de>,
+        {
+            self.deserialize_scalar(visitor)
+        }
+        #[cfg(not(feature = "i128"))]
+        fn deserialize_i128<V>(self, _visitor: V) -> Result<V::Value>
+        where
+            V: Visitor<'de>,
+        {
+            Err(de::Error::custom("i128 is not supported.  Enable the `i128` feature of `serde-yaml`"))
+        }
+    }
+
     fn deserialize_u8<V>(self, visitor: V) -> Result<V::Value>
     where
         V: Visitor<'de>,
@@ -713,6 +740,23 @@ impl<'de, 'a, 'r> de::Deserializer<'de> for &'r mut Deserializer<'a> {
         self.deserialize_scalar(visitor)
     }
 
+    serde_if_integer128! {
+        #[cfg(feature = "i128")]
+        fn deserialize_u128<V>(self, visitor: V) -> Result<V::Value>
+        where
+            V: Visitor<'de>,
+        {
+            self.deserialize_scalar(visitor)
+        }
+        #[cfg(not(feature = "i128"))]
+        fn deserialize_u128<V>(self, _visitor: V) -> Result<V::Value>
+        where
+            V: Visitor<'de>,
+        {
+            Err(de::Error::custom("u128 is not supported.  Enable the `i128` feature of `serde-yaml`"))
+        }
+    }
+
     fn deserialize_f32<V>(self, visitor: V) -> Result<V::Value>
     where
         V: Visitor<'de>,

src/lib.rs

@@ -59,6 +59,16 @@
 //! assert_eq!(point, deserialized_point);
 //! # }
 //! ```
+//!
+//! ## 128 bit numbers
+//!
+//! Support for `i128` and `u128` on Rust toolchains after `1.26.0` is enabled
+//! through the `i128` feature.  Add the following to `Cargo.toml`:
+//!
+//! ```toml,ignore
+//! [dependencies.serde-yaml]
+//! features = ["i128"]
+//! ```
 
 #![doc(html_root_url = "https://docs.rs/serde_yaml/0.8.5")]
 #![deny(missing_docs)]
@@ -88,6 +98,8 @@
     result_unwrap_used,
 ))]
 
+#[macro_use]
+extern crate cfg_if;
 extern crate dtoa;
 extern crate linked_hash_map;
 #[macro_use]