Merge pull request #24 from matthiasbeyer/high-level-fns

High level fns

6 files changed, 88 insertions, 9 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 80e3814..a33fd38 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,13 @@
 This changelog was started with the 0.4.0 release, so there are no logs before
 that version.
 
+# Next
+
+* Added method for requesting a type directly from the TOML document:
+  The method returns the requested type directly, or fails with
+  `Err(_)` and appropriate message:
+  `document.read_string(path) -> Result<String, Error>` (for example)
+
 # 0.4.0
 
 * Updated the `error-chain` dependency from `0.10` to `0.11`.
diff --git a/src/delete.rs b/src/delete.rs
index 1146a36..4a97809 100644
--- a/src/delete.rs
+++ b/src/delete.rs
@@ -78,15 +78,7 @@ impl TomlValueDeleteExt for Value {
 
         #[inline]
         fn name_of_val(val: Option<&Value>) -> &'static str {
-            val.map(|v| match v {
-                &Value::Array(_)    => "Array",
-                &Value::Boolean(_)  => "Boolean",
-                &Value::Datetime(_) => "Datetime",
-                &Value::Float(_)    => "Float",
-                &Value::Integer(_)  => "Integer",
-                &Value::String(_)   => "String",
-                &Value::Table(_)    => "Table",
-            }).unwrap_or("None")
+            val.map(::util::name_of_val).unwrap_or("None")
         }
 
         if last_token.is_none() {
diff --git a/src/error.rs b/src/error.rs
index 7cfca59..895f4ea 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -81,5 +81,15 @@ error_chain! {
             display("Cannot delete in array at {}, array has length {}", idx, arrlen)
         }
 
+        TypeError(requested: &'static str, got: &'static str) {
+            description("Type error")
+            display("Type Error. Requested {}, but got {}", requested, got)
+        }
+
+        NotAvailable(query: String) {
+            description("Value missing error")
+            display("Value at '{}' not there", query)
+        }
+
     }
 }
diff --git a/src/lib.rs b/src/lib.rs
index 61cf752..ec46278 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -31,6 +31,7 @@ pub mod set;
 pub mod insert;
 pub mod delete;
 pub mod value;
+mod util;
 
 // private modules
 
diff --git a/src/read.rs b/src/read.rs
index 3d4ff39..391d5ec 100644
--- a/src/read.rs
+++ b/src/read.rs
@@ -43,6 +43,41 @@ impl<'doc> TomlValueReadExt<'doc> for Value {
 
 }
 
+pub trait TomlValueReadTypeExt<'doc> {
+    fn read_string(&'doc self, query: &str) -> Result<String>;
+    fn read_int(&'doc self, query: &str) -> Result<i64>;
+    fn read_float(&'doc self, query: &str) -> Result<f64>;
+    fn read_bool(&'doc self, query: &str) -> Result<bool>;
+}
+
+macro_rules! make_type_getter {
+    ($fnname:ident, $rettype:ty, $typename:expr, $matcher:pat => $implementation:expr) => {
+        fn $fnname(&'doc self, query: &str) -> Result<$rettype> {
+            self.read_with_seperator(query, '.').and_then(|o| match o {
+                $matcher => $implementation,
+                Some(o)  => Err(ErrorKind::TypeError($typename, ::util::name_of_val(&o)).into()),
+                None     => Err(ErrorKind::NotAvailable(String::from(query)).into()),
+            })
+        }
+    };
+}
+
+impl<'doc, T> TomlValueReadTypeExt<'doc> for T
+    where T: TomlValueReadExt<'doc>
+{
+    make_type_getter!(read_string, String, "String",
+                      Some(&Value::String(ref obj)) => Ok(obj.clone()));
+
+    make_type_getter!(read_int, i64, "Integer",
+                      Some(&Value::Integer(obj)) => Ok(obj));
+
+    make_type_getter!(read_float, f64, "Float",
+                      Some(&Value::Float(obj)) => Ok(obj));
+
+    make_type_getter!(read_bool, bool, "Boolean",
+                      Some(&Value::Boolean(obj)) => Ok(obj));
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
@@ -209,3 +244,23 @@ mod test {
 
 }
 
+#[cfg(test)]
+mod high_level_fn_test {
+    use super::*;
+    use toml::from_str as toml_from_str;
+
+    #[test]
+    fn test_read_table_value() {
+        let toml : Value = toml_from_str(r#"
+        [table]
+        a = 1
+        "#).unwrap();
+
+        let val  = toml.read_int(&String::from("table.a"));
+
+        assert!(val.is_ok());
+        assert_eq!(val.unwrap(), 1);
+    }
+
+}
+
diff --git a/src/util.rs b/src/util.rs
new file mode 100644
index 0000000..5c54806
--- /dev/null
+++ b/src/util.rs
@@ -0,0 +1,14 @@
+use toml::Value;
+
+pub fn name_of_val(val: &Value) -> &'static str {
+    match *val {
+        Value::Array(_)    => "Array",
+        Value::Boolean(_)  => "Boolean",
+        Value::Datetime(_) => "Datetime",
+        Value::Float(_)    => "Float",
+        Value::Integer(_)  => "Integer",
+        Value::String(_)   => "String",
+        Value::Table(_)    => "Table",
+    }
+}
+