1 files changed, 205 insertions, 0 deletions
diff --git a/src/decoder/mod.rs b/src/decoder/mod.rs
new file mode 100644
index 0000000..675e0ca
--- /dev/null
+++ b/src/decoder/mod.rs
@@ -0,0 +1,205 @@
+use std::error;
+use std::fmt;
+
+use Value;
+use self::DecodeErrorKind::*;
+
+#[cfg(feature = "rustc-serialize")] mod rustc_serialize;
+
+/// A structure to transform TOML values into Rust values.
+///
+/// This decoder implements the serialization `Decoder` interface, allowing
+/// `Decodable` types to be generated by this decoder. The input is any
+/// arbitrary TOML value.
+pub struct Decoder {
+    /// The TOML value left over after decoding. This can be used to inspect
+    /// whether fields were decoded or not.
+    pub toml: Option<Value>,
+    cur_field: Option<String>,
+}
+
+/// Description for errors which can occur while decoding a type.
+#[derive(PartialEq, Debug)]
+pub struct DecodeError {
+    /// Field that this error applies to.
+    pub field: Option<String>,
+    /// The type of error which occurred while decoding,
+    pub kind: DecodeErrorKind,
+}
+
+/// Enumeration of possible errors which can occur while decoding a structure.
+#[derive(PartialEq, Debug)]
+pub enum DecodeErrorKind {
+    /// An error flagged by the application, e.g. value out of range
+    ApplicationError(String),
+    /// A field was expected, but none was found.
+    ExpectedField(/* type */ Option<&'static str>),
+    /// A field was found, but it had the wrong type.
+    ExpectedType(/* expected */ &'static str, /* found */ &'static str),
+    /// The nth map key was expected, but none was found.
+    ExpectedMapKey(usize),
+    /// The nth map element was expected, but none was found.
+    ExpectedMapElement(usize),
+    /// An enum decoding was requested, but no variants were supplied
+    NoEnumVariants,
+    /// The unit type was being decoded, but a non-zero length string was found
+    NilTooLong,
+    /// There was an error with the syntactical structure of the TOML.
+    SyntaxError,
+    /// The end of the TOML input was reached too soon
+    EndOfStream,
+}
+
+/// Decodes a TOML value into a decodable type.
+///
+/// This function will consume the given TOML value and attempt to decode it
+/// into the type specified. If decoding fails, `None` will be returned. If a
+/// finer-grained error is desired, then it is recommended to use `Decodable`
+/// directly.
+#[cfg(feature = "rustc-serialize")]
+pub fn decode<T: ::rustc_serialize::Decodable>(toml: Value) -> Option<T> {
+    ::rustc_serialize::Decodable::decode(&mut Decoder::new(toml)).ok()
+}
+
+/// Decodes a TOML value into a decodable type.
+///
+/// This function will consume the given TOML value and attempt to decode it
+/// into the type specified. If decoding fails, `None` will be returned. If a
+/// finer-grained error is desired, then it is recommended to use `Decodable`
+/// directly.
+#[cfg(all(not(feature = "rustc-serialize"), feature = "serde"))]
+pub fn decode<T: ::serde::Deserialize>(toml: Value) -> Option<T> {
+    ::serde::Deserialize::deserialize(&mut Decoder::new(toml)).ok()
+}
+
+/// Decodes a string into a toml-encoded value.
+///
+/// This function will parse the given string into a TOML value, and then parse
+/// the TOML value into the desired type. If any error occurs `None` is return.
+///
+/// If more fine-grained errors are desired, these steps should be driven
+/// manually.
+#[cfg(feature = "rustc-serialize")]
+pub fn decode_str<T: ::rustc_serialize::Decodable>(s: &str) -> Option<T> {
+    ::Parser::new(s).parse().and_then(|t| decode(Value::Table(t)))
+}
+
+/// Decodes a string into a toml-encoded value.
+///
+/// This function will parse the given string into a TOML value, and then parse
+/// the TOML value into the desired type. If any error occurs `None` is return.
+///
+/// If more fine-grained errors are desired, these steps should be driven
+/// manually.
+#[cfg(all(not(feature = "rustc-serialize"), feature = "serde"))]
+pub fn decode_str<T: ::serde::Deserialize>(s: &str) -> Option<T> {
+    ::Parser::new(s).parse().and_then(|t| decode(Value::Table(t)))
+}
+
+impl Decoder {
+    /// Creates a new decoder, consuming the TOML value to decode.
+    ///
+    /// This decoder can be passed to the `Decodable` methods or driven
+    /// manually.
+    pub fn new(toml: Value) -> Decoder {
+        Decoder { toml: Some(toml), cur_field: None }
+    }
+
+    fn sub_decoder(&self, toml: Option<Value>, field: &str) -> Decoder {
+        Decoder {
+            toml: toml,
+            cur_field: if field.len() == 0 {
+                self.cur_field.clone()
+            } else {
+                match self.cur_field {
+                    None => Some(format!("{}", field)),
+                    Some(ref s) => Some(format!("{}.{}", s, field))
+                }
+            }
+        }
+    }
+
+    fn err(&self, kind: DecodeErrorKind) -> DecodeError {
+        DecodeError {
+            field: self.cur_field.clone(),
+            kind: kind,
+        }
+    }
+
+    fn mismatch(&self, expected: &'static str,
+                found: &Option<Value>) -> DecodeError{
+        match *found {
+            Some(ref val) => self.err(ExpectedType(expected, val.type_str())),
+            None => self.err(ExpectedField(Some(expected))),
+        }
+    }
+}
+
+impl fmt::Display for DecodeError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        try!(match self.kind {
+            ApplicationError(ref err) => {
+                write!(f, "{}", err)
+            }
+            ExpectedField(expected_type) => {
+                match expected_type {
+                    Some("table") => write!(f, "expected a section"),
+                    Some(e) => write!(f, "expected a value of type `{}`", e),
+                    None => write!(f, "expected a value"),
+                }
+            }
+            ExpectedType(expected, found) => {
+                fn humanize(s: &str) -> String {
+                    if s == "section" {
+                        format!("a section")
+                    } else {
+                        format!("a value of type `{}`", s)
+                    }
+                }
+                write!(f, "expected {}, but found {}",
+                       humanize(expected),
+                       humanize(found))
+            }
+            ExpectedMapKey(idx) => {
+                write!(f, "expected at least {} keys", idx + 1)
+            }
+            ExpectedMapElement(idx) => {
+                write!(f, "expected at least {} elements", idx + 1)
+            }
+            NoEnumVariants => {
+                write!(f, "expected an enum variant to decode to")
+            }
+            NilTooLong => {
+                write!(f, "expected 0-length string")
+            }
+            SyntaxError => {
+                write!(f, "syntax error")
+            }
+            EndOfStream => {
+                write!(f, "end of stream")
+            }
+        });
+        match self.field {
+            Some(ref s) => {
+                write!(f, " for the key `{}`", s)
+            }
+            None => Ok(())
+        }
+    }
+}
+
+impl error::Error for DecodeError {
+    fn description(&self) -> &str {
+        match self.kind {
+            ApplicationError(ref s) => &**s,
+            ExpectedField(..) => "expected a field",
+            ExpectedType(..) => "expected a type",
+            ExpectedMapKey(..) => "expected a map key",
+            ExpectedMapElement(..) => "expected a map element",
+            NoEnumVariants => "no enum variants to decode to",
+            NilTooLong => "nonzero length string representing nil",
+            SyntaxError => "syntax error",
+            EndOfStream => "end of stream",
+        }
+    }
+}