mockchain: Implement FromStr for BlockDate

chain-impl-mockchain/src/block.rs

@@ -3,7 +3,7 @@ use crate::key::{Hash, PrivateKey, PublicKey, Signature};
 use crate::transaction::*;
 use chain_core::property;
 
-use std::fmt;
+use std::{error, fmt, num::ParseIntError, str};
 
 /// Non unique identifier of the transaction position in the
 /// blockchain. There may be many transactions related to the same
@@ -107,6 +107,51 @@ impl fmt::Display for BlockDate {
     }
 }
 
+#[derive(Debug)]
+pub enum BlockDateParseError {
+    DotMissing,
+    BadEpochId(ParseIntError),
+    BadSlotId(ParseIntError),
+}
+
+const EXPECT_FORMAT_MESSAGE: &'static str = "expected block date format EPOCH.SLOT";
+
+impl fmt::Display for BlockDateParseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use BlockDateParseError::*;
+        match self {
+            DotMissing => write!(f, "{}", EXPECT_FORMAT_MESSAGE),
+            BadEpochId(_) => write!(f, "invalid epoch ID, {}", EXPECT_FORMAT_MESSAGE),
+            BadSlotId(_) => write!(f, "invalid slot ID, {}", EXPECT_FORMAT_MESSAGE),
+        }
+    }
+}
+
+impl error::Error for BlockDateParseError {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        use BlockDateParseError::*;
+        match self {
+            DotMissing => None,
+            BadEpochId(e) => Some(e),
+            BadSlotId(e) => Some(e),
+        }
+    }
+}
+
+impl str::FromStr for BlockDate {
+    type Err = BlockDateParseError;
+
+    fn from_str(s: &str) -> Result<BlockDate, BlockDateParseError> {
+        let (ep, sp) = match s.find('.') {
+            None => return Err(BlockDateParseError::DotMissing),
+            Some(pos) => s.split_at(pos),
+        };
+        let epoch = str::parse::<u64>(ep).map_err(|e| BlockDateParseError::BadEpochId(e))?;
+        let slot_id = str::parse::<u64>(sp).map_err(|e| BlockDateParseError::BadSlotId(e))?;
+        Ok(BlockDate { epoch, slot_id })
+    }
+}
+
 impl property::Block for Block {
     type Id = Hash;
     type Date = BlockDate;