Merge pull request #217 from dtolnay/macro

A toml macro

2 files changed, 376 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
index c4a7e9d..1c4842b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -166,3 +166,6 @@ pub mod de;
 #[doc(no_inline)]
 pub use de::{from_slice, from_str, Deserializer};
 mod tokens;
+
+#[doc(hidden)]
+pub mod macros;
diff --git a/src/macros.rs b/src/macros.rs
new file mode 100644
index 0000000..7a2bcd3
--- /dev/null
+++ b/src/macros.rs
@@ -0,0 +1,373 @@
+pub use serde::de::{Deserialize, IntoDeserializer};
+
+use value::{Value, Table, Array};
+
+/// Construct a [`toml::Value`] from TOML syntax.
+///
+/// [`toml::Value`]: value/enum.Value.html
+///
+/// ```rust
+/// #[macro_use]
+/// extern crate toml;
+///
+/// fn main() {
+///     let cargo_toml = toml! {
+///         [package]
+///         name = "toml"
+///         version = "0.4.5"
+///         authors = ["Alex Crichton <alex@alexcrichton.com>"]
+///
+///         [badges]
+///         travis-ci = { repository = "alexcrichton/toml-rs" }
+///
+///         [dependencies]
+///         serde = "1.0"
+///
+///         [dev-dependencies]
+///         serde_derive = "1.0"
+///         serde_json = "1.0"
+///     };
+///
+///     println!("{:#?}", cargo_toml);
+/// }
+/// ```
+#[macro_export]
+macro_rules! toml {
+    ($($toml:tt)+) => {{
+        let table = $crate::value::Table::new();
+        let mut root = $crate::Value::Table(table);
+        toml_internal!(@toplevel root [] $($toml)+);
+        root
+    }};
+}
+
+// TT-muncher to parse TOML syntax into a toml::Value.
+//
+//    @toplevel -- Parse tokens outside of an inline table or inline array. In
+//                 this state, `[table headers]` and `[[array headers]]` are
+//                 allowed and `key = value` pairs are not separated by commas.
+//
+//    @topleveldatetime -- Helper to parse a Datetime from string and insert it
+//                 into a table, continuing in the @toplevel state.
+//
+//    @path -- Turn a path segment into a string. Segments that look like idents
+//                 are stringified, while quoted segments like `"cfg(windows)"`
+//                 are not.
+//
+//    @value -- Parse the value part of a `key = value` pair, which may be a
+//                 primitive or inline table or inline array.
+//
+//    @table -- Parse the contents of an inline table, returning them as a
+//                 toml::Value::Table.
+//
+//    @tabledatetime -- Helper to parse a Datetime from string and insert it
+//                 into a table, continuing in the @table state.
+//
+//    @array -- Parse the contents of an inline array, returning them as a
+//                 toml::Value::Array.
+//
+//    @arraydatetime -- Helper to parse a Datetime from string and push it into
+//                 an array, continuing in the @array state.
+//
+//    @trailingcomma -- Helper to append a comma to a sequence of tokens if the
+//                 sequence is non-empty and does not already end in a trailing
+//                 comma.
+//
+#[macro_export]
+#[doc(hidden)]
+macro_rules! toml_internal {
+    // Base case, no elements remaining.
+    (@toplevel $root:ident [$($path:tt)*]) => {};
+
+    // Parse negative number `key = -value`.
+    (@toplevel $root:ident [$($path:tt)*] $($k:tt)-+ = - $v:tt $($rest:tt)*) => {
+        toml_internal!(@toplevel $root [$($path)*] $($k)-+ = (-$v) $($rest)*);
+    };
+
+    // Parse offset datetime `key = 1979-05-27T00:32:00.999999-07:00`.
+    (@toplevel $root:ident [$($path:tt)*] $($k:tt)-+ = $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt . $frac:tt - $tzh:tt : $tzm:tt $($rest:tt)*) => {
+        toml_internal!(@topleveldatetime $root [$($path)*] $($k)-+ = ($yr - $mo - $dhr : $min : $sec . $frac - $tzh : $tzm) $($rest)*);
+    };
+
+    // Parse offset datetime `key = 1979-05-27T00:32:00-07:00`.
+    (@toplevel $root:ident [$($path:tt)*] $($k:tt)-+ = $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt - $tzh:tt : $tzm:tt $($rest:tt)*) => {
+        toml_internal!(@topleveldatetime $root [$($path)*] $($k)-+ = ($yr - $mo - $dhr : $min : $sec - $tzh : $tzm) $($rest)*);
+    };
+
+    // Parse local datetime `key = 1979-05-27T00:32:00.999999`.
+    (@toplevel $root:ident [$($path:tt)*] $($k:tt)-+ = $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt . $frac:tt $($rest:tt)*) => {
+        toml_internal!(@topleveldatetime $root [$($path)*] $($k)-+ = ($yr - $mo - $dhr : $min : $sec . $frac) $($rest)*);
+    };
+
+    // Parse offset datetime `key = 1979-05-27T07:32:00Z` and local datetime `key = 1979-05-27T07:32:00`.
+    (@toplevel $root:ident [$($path:tt)*] $($k:tt)-+ = $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt $($rest:tt)*) => {
+        toml_internal!(@topleveldatetime $root [$($path)*] $($k)-+ = ($yr - $mo - $dhr : $min : $sec) $($rest)*);
+    };
+
+    // Parse local date `key = 1979-05-27`.
+    (@toplevel $root:ident [$($path:tt)*] $($k:tt)-+ = $yr:tt - $mo:tt - $day:tt $($rest:tt)*) => {
+        toml_internal!(@topleveldatetime $root [$($path)*] $($k)-+ = ($yr - $mo - $day) $($rest)*);
+    };
+
+    // Parse local time `key = 00:32:00.999999`.
+    (@toplevel $root:ident [$($path:tt)*] $($k:tt)-+ = $hr:tt : $min:tt : $sec:tt . $frac:tt $($rest:tt)*) => {
+        toml_internal!(@topleveldatetime $root [$($path)*] $($k)-+ = ($hr : $min : $sec . $frac) $($rest)*);
+    };
+
+    // Parse local time `key = 07:32:00`.
+    (@toplevel $root:ident [$($path:tt)*] $($k:tt)-+ = $hr:tt : $min:tt : $sec:tt $($rest:tt)*) => {
+        toml_internal!(@topleveldatetime $root [$($path)*] $($k)-+ = ($hr : $min : $sec) $($rest)*);
+    };
+
+    // Parse any other `key = value` including string, inline array, inline
+    // table, number, and boolean.
+    (@toplevel $root:ident [$($path:tt)*] $($k:tt)-+ = $v:tt $($rest:tt)*) => {
+        $crate::macros::insert_toml(
+            &mut $root,
+            &[$($path)* &concat!($("-", toml_internal!(@path $k),)+)[1..]],
+            toml_internal!(@value $v));
+        toml_internal!(@toplevel $root [$($path)*] $($rest)*);
+    };
+
+    // Parse array header `[[bin]]`.
+    (@toplevel $root:ident $oldpath:tt [[$($($path:tt)-+).+]] $($rest:tt)*) => {
+        $crate::macros::push_toml(
+            &mut $root,
+            &[$(&concat!($("-", toml_internal!(@path $path),)+)[1..],)+]);
+        toml_internal!(@toplevel $root [$(&concat!($("-", toml_internal!(@path $path),)+)[1..],)+] $($rest)*);
+    };
+
+    // Parse table header `[patch.crates-io]`.
+    (@toplevel $root:ident $oldpath:tt [$($($path:tt)-+).+] $($rest:tt)*) => {
+        $crate::macros::insert_toml(
+            &mut $root,
+            &[$(&concat!($("-", toml_internal!(@path $path),)+)[1..],)+],
+            $crate::Value::Table($crate::value::Table::new()));
+        toml_internal!(@toplevel $root [$(&concat!($("-", toml_internal!(@path $path),)+)[1..],)+] $($rest)*);
+    };
+
+    // Parse datetime from string and insert into table.
+    (@topleveldatetime $root:ident [$($path:tt)*] $($k:tt)-+ = ($($datetime:tt)+) $($rest:tt)*) => {
+        $crate::macros::insert_toml(
+            &mut $root,
+            &[$($path)* &concat!($("-", toml_internal!(@path $k),)+)[1..]],
+            $crate::Value::Datetime(concat!($(stringify!($datetime)),+).parse().unwrap()));
+        toml_internal!(@toplevel $root [$($path)*] $($rest)*);
+    };
+
+    // Turn a path segment into a string.
+    (@path $ident:ident) => {
+        stringify!($ident)
+    };
+
+    // For a path segment that is not an ident, expect that it is already a
+    // quoted string, like in `[target."cfg(windows)".dependencies]`.
+    (@path $quoted:tt) => {
+        $quoted
+    };
+
+    // Construct a Value from an inline table.
+    (@value { $($inline:tt)* }) => {{
+        let mut table = $crate::value::Table::new();
+        toml_internal!(@trailingcomma (@table table) $($inline)*);
+        $crate::Value::Table(table)
+    }};
+
+    // Construct a Value from an inline array.
+    (@value [ $($inline:tt)* ]) => {{
+        let mut array = $crate::value::Array::new();
+        toml_internal!(@trailingcomma (@array array) $($inline)*);
+        $crate::Value::Array(array)
+    }};
+
+    // Construct a Value from any other type, probably string or boolean or number.
+    (@value $v:tt) => {{
+        // TODO: Implement this with something like serde_json::to_value instead.
+        let de = $crate::macros::IntoDeserializer::<$crate::de::Error>::into_deserializer($v);
+        <$crate::Value as $crate::macros::Deserialize>::deserialize(de).unwrap()
+    }};
+
+    // Base case of inline table.
+    (@table $root:ident) => {};
+
+    // Parse negative number `key = -value`.
+    (@table $root:ident $($k:tt)-+ = - $v:tt , $($rest:tt)*) => {
+        toml_internal!(@table $root $($k)-+ = (-$v) , $($rest)*);
+    };
+
+    // Parse offset datetime `key = 1979-05-27T00:32:00.999999-07:00`.
+    (@table $root:ident $($k:tt)-+ = $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt . $frac:tt - $tzh:tt : $tzm:tt , $($rest:tt)*) => {
+        toml_internal!(@tabledatetime $root $($k)-+ = ($yr - $mo - $dhr : $min : $sec . $frac - $tzh : $tzm) $($rest)*);
+    };
+
+    // Parse offset datetime `key = 1979-05-27T00:32:00-07:00`.
+    (@table $root:ident $($k:tt)-+ = $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt - $tzh:tt : $tzm:tt , $($rest:tt)*) => {
+        toml_internal!(@tabledatetime $root $($k)-+ = ($yr - $mo - $dhr : $min : $sec - $tzh : $tzm) $($rest)*);
+    };
+
+    // Parse local datetime `key = 1979-05-27T00:32:00.999999`.
+    (@table $root:ident $($k:tt)-+ = $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt . $frac:tt , $($rest:tt)*) => {
+        toml_internal!(@tabledatetime $root $($k)-+ = ($yr - $mo - $dhr : $min : $sec . $frac) $($rest)*);
+    };
+
+    // Parse offset datetime `key = 1979-05-27T07:32:00Z` and local datetime `key = 1979-05-27T07:32:00`.
+    (@table $root:ident $($k:tt)-+ = $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt , $($rest:tt)*) => {
+        toml_internal!(@tabledatetime $root $($k)-+ = ($yr - $mo - $dhr : $min : $sec) $($rest)*);
+    };
+
+    // Parse local date `key = 1979-05-27`.
+    (@table $root:ident $($k:tt)-+ = $yr:tt - $mo:tt - $day:tt , $($rest:tt)*) => {
+        toml_internal!(@tabledatetime $root $($k)-+ = ($yr - $mo - $day) $($rest)*);
+    };
+
+    // Parse local time `key = 00:32:00.999999`.
+    (@table $root:ident $($k:tt)-+ = $hr:tt : $min:tt : $sec:tt . $frac:tt , $($rest:tt)*) => {
+        toml_internal!(@tabledatetime $root $($k)-+ = ($hr : $min : $sec . $frac) $($rest)*);
+    };
+
+    // Parse local time `key = 07:32:00`.
+    (@table $root:ident $($k:tt)-+ = $hr:tt : $min:tt : $sec:tt , $($rest:tt)*) => {
+        toml_internal!(@tabledatetime $root $($k)-+ = ($hr : $min : $sec) $($rest)*);
+    };
+
+    // Parse any other type, probably string or boolean or number.
+    (@table $root:ident $($k:tt)-+ = $v:tt , $($rest:tt)*) => {
+        $root.insert(
+            concat!($("-", toml_internal!(@path $k),)+)[1..].to_owned(),
+            toml_internal!(@value $v));
+        toml_internal!(@table $root $($rest)*);
+    };
+
+    // Parse a Datetime from string and continue in @table state.
+    (@tabledatetime $root:ident $($k:tt)-+ = ($($datetime:tt)*) $($rest:tt)*) => {
+        $root.insert(
+            concat!($("-", toml_internal!(@path $k),)+)[1..].to_owned(),
+            $crate::Value::Datetime(concat!($(stringify!($datetime)),+).parse().unwrap()));
+        toml_internal!(@table $root $($rest)*);
+    };
+
+    // Base case of inline array.
+    (@array $root:ident) => {};
+
+    // Parse negative number `-value`.
+    (@array $root:ident - $v:tt , $($rest:tt)*) => {
+        toml_internal!(@array $root (-$v) , $($rest)*);
+    };
+
+    // Parse offset datetime `1979-05-27T00:32:00.999999-07:00`.
+    (@array $root:ident $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt . $frac:tt - $tzh:tt : $tzm:tt , $($rest:tt)*) => {
+        toml_internal!(@arraydatetime $root ($yr - $mo - $dhr : $min : $sec . $frac - $tzh : $tzm) $($rest)*);
+    };
+
+    // Parse offset datetime `1979-05-27T00:32:00-07:00`.
+    (@array $root:ident $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt - $tzh:tt : $tzm:tt , $($rest:tt)*) => {
+        toml_internal!(@arraydatetime $root ($yr - $mo - $dhr : $min : $sec - $tzh : $tzm) $($rest)*);
+    };
+
+    // Parse local datetime `1979-05-27T00:32:00.999999`.
+    (@array $root:ident $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt . $frac:tt , $($rest:tt)*) => {
+        toml_internal!(@arraydatetime $root ($yr - $mo - $dhr : $min : $sec . $frac) $($rest)*);
+    };
+
+    // Parse offset datetime `1979-05-27T07:32:00Z` and local datetime `1979-05-27T07:32:00`.
+    (@array $root:ident $yr:tt - $mo:tt - $dhr:tt : $min:tt : $sec:tt , $($rest:tt)*) => {
+        toml_internal!(@arraydatetime $root ($yr - $mo - $dhr : $min : $sec) $($rest)*);
+    };
+
+    // Parse local date `1979-05-27`.
+    (@array $root:ident $yr:tt - $mo:tt - $day:tt , $($rest:tt)*) => {
+        toml_internal!(@arraydatetime $root ($yr - $mo - $day) $($rest)*);
+    };
+
+    // Parse local time `00:32:00.999999`.
+    (@array $root:ident $hr:tt : $min:tt : $sec:tt . $frac:tt , $($rest:tt)*) => {
+        toml_internal!(@arraydatetime $root ($hr : $min : $sec . $frac) $($rest)*);
+    };
+
+    // Parse local time `07:32:00`.
+    (@array $root:ident $hr:tt : $min:tt : $sec:tt , $($rest:tt)*) => {
+        toml_internal!(@arraydatetime $root ($hr : $min : $sec) $($rest)*);
+    };
+
+    // Parse any other type, probably string or boolean or number.
+    (@array $root:ident $v:tt , $($rest:tt)*) => {
+        $root.push(toml_internal!(@value $v));
+        toml_internal!(@array $root $($rest)*);
+    };
+
+    // Parse a Datetime from string and continue in @array state.
+    (@arraydatetime $root:ident ($($datetime:tt)*) $($rest:tt)*) => {
+        $root.push($crate::Value::Datetime(concat!($(stringify!($datetime)),+).parse().unwrap()));
+        toml_internal!(@array $root $($rest)*);
+    };
+
+    // No trailing comma required if the tokens are empty.
+    (@trailingcomma ($($args:tt)*)) => {
+        toml_internal!($($args)*);
+    };
+
+    // Tokens end with a trailing comma, do not append another one.
+    (@trailingcomma ($($args:tt)*) ,) => {
+        toml_internal!($($args)* ,);
+    };
+
+    // Tokens end with something other than comma, append a trailing comma.
+    (@trailingcomma ($($args:tt)*) $last:tt) => {
+        toml_internal!($($args)* $last ,);
+    };
+
+    // Not yet at the last token.
+    (@trailingcomma ($($args:tt)*) $first:tt $($rest:tt)+) => {
+        toml_internal!(@trailingcomma ($($args)* $first) $($rest)+);
+    };
+}
+
+// Called when parsing a `key = value` pair.
+// Inserts an entry into the table at the given path.
+pub fn insert_toml(root: &mut Value, path: &[&str], value: Value) {
+    *traverse(root, path) = value;
+}
+
+// Called when parsing an `[[array header]]`.
+// Pushes an empty table onto the array at the given path.
+pub fn push_toml(root: &mut Value, path: &[&str]) {
+    let target = traverse(root, path);
+    if !target.is_array() {
+        *target = Value::Array(Array::new());
+    }
+    target.as_array_mut().unwrap().push(Value::Table(Table::new()));
+}
+
+fn traverse<'a>(root: &'a mut Value, path: &[&str]) -> &'a mut Value {
+    let mut cur = root;
+    for &key in path {
+        // Lexical lifetimes :D
+        let cur1 = cur;
+        let cur2;
+
+        // From the TOML spec:
+        //
+        // > Each double-bracketed sub-table will belong to the most recently
+        // > defined table element above it.
+        if cur1.is_array() {
+            cur2 = cur1.as_array_mut().unwrap().last_mut().unwrap();
+        } else {
+            cur2 = cur1;
+        };
+
+        // We are about to index into this value, so it better be a table.
+        if !cur2.is_table() {
+            *cur2 = Value::Table(Table::new());
+        }
+
+        if !cur2.as_table().unwrap().contains_key(key) {
+            // Insert an empty table for the next loop iteration to point to.
+            let empty = Value::Table(Table::new());
+            cur2.as_table_mut().unwrap().insert(key.to_owned(), empty);
+        }
+
+        // Step into the current table.
+        cur = cur2.as_table_mut().unwrap().get_mut(key).unwrap();
+    }
+    cur
+}