Add StringSource

This patch adds a type for a String buffer as a source for the
configuration as well as format parser interfaces.

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

5 files changed, 95 insertions, 1 deletions

diff --git a/src/element/mod.rs b/src/element/mod.rs
index 3425bed..6059651 100644
--- a/src/element/mod.rs
+++ b/src/element/mod.rs
@@ -27,7 +27,7 @@ pub trait AsConfigElement {
 }
 
 #[cfg(feature = "json")]
-mod json;
+pub mod json;
 
 #[cfg(feature = "toml")]
 mod toml;
diff --git a/src/lib.rs b/src/lib.rs
index 7102d4a..4ddb7a9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,3 +7,4 @@ mod source;
 
 pub use crate::config::Config;
 pub use crate::source::ConfigSource;
+pub use crate::source::StringSource;
diff --git a/src/source/format.rs b/src/source/format.rs
new file mode 100644
index 0000000..b2e6551
--- /dev/null
+++ b/src/source/format.rs
@@ -0,0 +1,23 @@
+use crate::element::AsConfigElement;
+
+use super::SourceError;
+
+pub trait FormatParser: std::fmt::Debug {
+    type Output: AsConfigElement + std::fmt::Debug + Sized;
+
+    fn parse(buffer: &str) -> Result<Self::Output, SourceError>;
+}
+
+#[cfg(feature = "json")]
+#[derive(Debug)]
+pub struct JsonFormatParser;
+
+#[cfg(feature = "json")]
+impl FormatParser for JsonFormatParser {
+    type Output = serde_json::Value;
+
+    fn parse(buffer: &str) -> Result<Self::Output, SourceError> {
+        serde_json::from_str(buffer).map_err(SourceError::JsonParserError)
+    }
+}
+
diff --git a/src/source.rs b/src/source/mod.rs
index 485da8a..3b2dd87 100644
--- a/src/source.rs
+++ b/src/source/mod.rs
@@ -1,11 +1,31 @@
 use crate::object::ConfigObject;
 
+mod format;
+mod string;
+
+pub use crate::source::string::StringSource;
+pub use crate::source::format::FormatParser;
+pub use crate::source::format::JsonFormatParser;
+
 pub trait ConfigSource: std::fmt::Debug {
     type Error: std::error::Error;
 
     fn load<'a>(&'a self) -> Result<ConfigObject<'a>, Self::Error>;
 }
 
+#[derive(Debug, thiserror::Error)]
+pub enum SourceError {
+    #[error("IO Error")]
+    Io(#[from] std::io::Error),
+
+    #[cfg(feature = "json")]
+    #[error("JSON Parser error")]
+    JsonParserError(#[from] serde_json::Error),
+
+    #[cfg(feature = "json")]
+    #[error("JSON load error")]
+    JsonLoadError(#[from] crate::element::json::JsonIntoConfigElementError),
+}
 
 #[cfg(test)]
 pub(crate) mod test_source {
@@ -35,3 +55,4 @@ pub(crate) mod test_source {
         }
     }
 }
+
diff --git a/src/source/string.rs b/src/source/string.rs
new file mode 100644
index 0000000..e09e7f2
--- /dev/null
+++ b/src/source/string.rs
@@ -0,0 +1,49 @@
+use crate::ConfigSource;
+use crate::description::ConfigSourceDescription;
+use crate::element::AsConfigElement;
+use crate::object::ConfigObject;
+use crate::source::format::FormatParser;
+
+use super::SourceError;
+
+#[derive(Debug)]
+pub struct StringSource<P: FormatParser + std::fmt::Debug> {
+    data: P::Output,
+}
+
+impl<P: FormatParser> StringSource<P> {
+    pub fn new(buffer: &str) -> Result<Self, SourceError> {
+        Ok(StringSource {
+            data: P::parse(buffer)?,
+        })
+    }
+}
+
+impl<P: FormatParser + std::fmt::Debug> ConfigSource for StringSource<P>
+    where SourceError: From<<<P as FormatParser>::Output as AsConfigElement>::Error>
+{
+    type Error = SourceError;
+
+    fn load<'a>(&'a self) -> Result<ConfigObject<'a>, Self::Error> {
+        let element = self.data
+            .as_config_element()?;
+
+        let desc = ConfigSourceDescription::Custom("String".to_string());
+        Ok(ConfigObject::new(element, desc))
+    }
+}
+
+#[cfg(test)]
+mod test_source_impl {
+    #[cfg(feature = "json")]
+    #[test]
+    fn test_json_string_source() {
+        use super::*;
+
+        let source = "{}";
+
+        let source = StringSource::<crate::source::JsonFormatParser>::new(source).unwrap();
+        let _object = source.load().unwrap();
+    }
+}
+