From e605d70af1333ab75561de72a00d088687a1fded Mon Sep 17 00:00:00 2001
From: Erick Tryzelaar <erick.tryzelaar@gmail.com>
Date: Fri, 3 Oct 2014 07:50:30 -0700
Subject: [PATCH] Add support for deserialization streams that have an option
 type

---
 serde2/src/bin.rs | 106 ++++++++++++++++++++++++++++++++++++++++------
 serde2/src/de2.rs |  43 +------------------
 2 files changed, 95 insertions(+), 54 deletions(-)

diff --git a/serde2/src/bin.rs b/serde2/src/bin.rs
index 55662d4e..e56826b6 100644
--- a/serde2/src/bin.rs
+++ b/serde2/src/bin.rs
@@ -8,6 +8,7 @@ enum Token {
     Null,
     Int(int),
     //String(String),
+    Optiony(bool),
     SeqStart(uint),
     //MapStart(uint),
     End,
@@ -23,7 +24,7 @@ enum Error {
 
 struct MyDeserializer<Iter> {
     tokens: Iter,
-    peeked: Option<Token>,
+    peeked: ::std::option::Option<Token>,
 }
 
 impl<Iter: Iterator<Token>> MyDeserializer<Iter> {
@@ -70,6 +71,12 @@ impl<Iter: Iterator<Token>> Deserializer<Error> for MyDeserializer<Iter> {
                 visitor.visit_string(self, v)
             }
             */
+            Some(Optiony(is_some)) => {
+                visitor.visit_option(self, MyOptionVisitor {
+                    is_some: is_some,
+                    finished: false,
+                })
+            }
             Some(SeqStart(len)) => {
                 visitor.visit_seq(self, MySeqVisitor { len: len })
             }
@@ -95,6 +102,15 @@ impl<Iter: Iterator<Token>> Deserializer<Error> for MyDeserializer<Iter> {
                 self.next();
                 Ok(None)
             }
+            Some(&Optiony(true)) => {
+                self.next();
+                let v = try!(Deserialize::deserialize(self));
+                Ok(Some(v))
+            }
+            Some(&Optiony(false)) => {
+                self.next();
+                Ok(None)
+            }
             _ => {
                 let v = try!(Deserialize::deserialize(self));
                 Ok(Some(v))
@@ -111,6 +127,32 @@ impl<Iter: Iterator<Token>> Deserializer<Error> for MyDeserializer<Iter> {
     }
 }
 
+struct MyOptionVisitor {
+    is_some: bool,
+    finished: bool,
+}
+
+impl<
+    Iter: Iterator<Token>,
+> de2::OptionVisitor<MyDeserializer<Iter>, Error> for MyOptionVisitor {
+    fn visit<
+        T: Deserialize<MyDeserializer<Iter>, Error>,
+    >(&mut self, d: &mut MyDeserializer<Iter>) -> Result<Option<T>, Error> {
+        if self.finished {
+            Err(d.syntax_error())
+        } else {
+            self.finished = true;
+
+            if self.is_some {
+                let v = try!(Deserialize::deserialize(d));
+                Ok(Some(v))
+            } else {
+                Ok(None)
+            }
+        }
+    }
+}
+
 struct MySeqVisitor {
     len: uint,
 }
@@ -220,16 +262,14 @@ mod json {
                 }
                 */
 
-                /*
                 fn visit_option<
                     Visitor: de2::OptionVisitor<D, E>,
                 >(&mut self, d: &mut D, mut visitor: Visitor) -> Result<Value, E> {
-                    match visitor.next(d) {
-                        Some(v) => v,
+                    match try!(visitor.visit(d)) {
+                        Some(value) => Ok(value),
                         None => Ok(Null),
                     }
                 }
-                */
 
                 fn visit_seq<
                     Visitor: de2::SeqVisitor<D, E>,
@@ -294,7 +334,7 @@ fn main() {
     let mut state = MyDeserializer::new(tokens.into_iter());
 
     let v: Result<Vec<int>, Error> = Deserialize::deserialize(&mut state);
-    println!("{}", v);
+    println!("vec:          {}", v);
 
     ////
 
@@ -307,7 +347,7 @@ fn main() {
     let mut state = MyDeserializer::new(tokens.into_iter());
 
     let v: Result<(int, int), Error> = Deserialize::deserialize(&mut state);
-    println!("{}", v);
+    println!("tuple:        {}", v);
 
     ////
 
@@ -320,7 +360,49 @@ fn main() {
     let mut state = MyDeserializer::new(tokens.into_iter());
 
     let v: Result<json::Value, Error> = Deserialize::deserialize(&mut state);
-    println!("{}", v);
+    println!("value:        {}", v);
+
+    ////
+
+    let tokens = vec!(
+        Optiony(true),
+        Int(1),
+    );
+    let mut state = MyDeserializer::new(tokens.into_iter());
+
+    let v: Result<Option<int>, Error> = Deserialize::deserialize(&mut state);
+    println!("optiony:      {}", v);
+
+    ////
+
+    let tokens = vec!(
+        Optiony(false),
+    );
+    let mut state = MyDeserializer::new(tokens.into_iter());
+
+    let v: Result<Option<int>, Error> = Deserialize::deserialize(&mut state);
+    println!("optiony:      {}", v);
+
+    ////
+
+    let tokens = vec!(
+        Optiony(true),
+        Int(1),
+    );
+    let mut state = MyDeserializer::new(tokens.into_iter());
+
+    let v: Result<json::Value, Error> = Deserialize::deserialize(&mut state);
+    println!("optiony value:{}", v);
+
+    ////
+
+    let tokens = vec!(
+        Optiony(false),
+    );
+    let mut state = MyDeserializer::new(tokens.into_iter());
+
+    let v: Result<json::Value, Error> = Deserialize::deserialize(&mut state);
+    println!("optiony value:{}", v);
 
     ////
 
@@ -330,7 +412,7 @@ fn main() {
     let mut state = MyDeserializer::new(tokens.into_iter());
 
     let v: Result<Option<int>, Error> = Deserialize::deserialize(&mut state);
-    println!("{}", v);
+    println!("option:       {}", v);
 
     ////
 
@@ -340,7 +422,7 @@ fn main() {
     let mut state = MyDeserializer::new(tokens.into_iter());
 
     let v: Result<Option<int>, Error> = Deserialize::deserialize(&mut state);
-    println!("{}", v);
+    println!("option:       {}", v);
 
     ////
 
@@ -350,7 +432,7 @@ fn main() {
     let mut state = MyDeserializer::new(tokens.into_iter());
 
     let v: Result<json::Value, Error> = Deserialize::deserialize(&mut state);
-    println!("{}", v);
+    println!("option value: {}", v);
 
     ////
 
@@ -360,7 +442,7 @@ fn main() {
     let mut state = MyDeserializer::new(tokens.into_iter());
 
     let v: Result<json::Value, Error> = Deserialize::deserialize(&mut state);
-    println!("{}", v);
+    println!("option value: {}", v);
 
     /*
     ////
diff --git a/serde2/src/de2.rs b/serde2/src/de2.rs
index b8c155e5..091c477d 100644
--- a/serde2/src/de2.rs
+++ b/serde2/src/de2.rs
@@ -31,13 +31,11 @@ pub trait Visitor<D: Deserializer<E>, R, E> {
         Err(d.syntax_error())
     }
 
-    /*
     fn visit_option<
         V: OptionVisitor<D, E>
     >(&mut self, d: &mut D, _visitor: V) -> Result<R, E> {
         Err(d.syntax_error())
     }
-    */
 
     fn visit_seq<
         V: SeqVisitor<D, E>
@@ -46,19 +44,11 @@ pub trait Visitor<D: Deserializer<E>, R, E> {
     }
 }
 
-/*
-pub trait OptionVisitor<D, R, T: Deserialize<D, E>, E> {
-    /*
-    fn next<
-        T: Deserialize<D, E>,
-    >(&mut self, d: &mut D) -> Option<Result<T, E>>;
-    */
-
+pub trait OptionVisitor<D, E> {
     fn visit<
         T: Deserialize<D, E>,
     >(&mut self, d: &mut D) -> Result<Option<T>, E>;
 }
-*/
 
 pub trait SeqVisitor<D, E> {
     fn next<
@@ -119,37 +109,6 @@ impl<
     E,
 > Deserialize<D, E> for Option<T> {
     fn deserialize(d: &mut D) -> Result<Option<T>, E> {
-        /*
-        struct Visitor;
-
-        impl<
-            R: Deserialize<D, E>,
-            D: Deserializer<E>,
-            E,
-        > self::OptionVisitor<D, E> for Visitor {
-            /*
-            fn visit_option<
-                V: OptionVisitor<D, E>,
-            >(&mut self, d: &mut D, mut visitor: V) -> Result<Option<R>, E> {
-                match visitor.next(d) {
-                    Some(value) => {
-                        Ok(Some(try!(value)))
-                    }
-                    None => {
-                        Ok(None)
-                    }
-                }
-            }
-            */
-
-            fn visit<
-                T: Deserialize<D, E>,
-            >(&mut self, d: &mut D, value: Option<T>) -> Result<Option<T>, E> {
-                Ok(value)
-            }
-        }
-        */
-
         d.visit_option()
     }
 }