From 7e8ee5ed9cad6484e9f13f81731b102ced58402e Mon Sep 17 00:00:00 2001
From: Adam Carpenter <gitlab@53hor.net>
Date: Tue, 9 Jul 2019 15:14:04 -0400
Subject: Init.

---
 meap/meap-code/ch3/ch3-parse-log.rs | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100755 meap/meap-code/ch3/ch3-parse-log.rs

(limited to 'meap/meap-code/ch3/ch3-parse-log.rs')

diff --git a/meap/meap-code/ch3/ch3-parse-log.rs b/meap/meap-code/ch3/ch3-parse-log.rs
new file mode 100755
index 0000000..b675aa1
--- /dev/null
+++ b/meap/meap-code/ch3/ch3-parse-log.rs
@@ -0,0 +1,35 @@
+#[derive(Debug)] // <1> Enable this enum to be printed to the screen via auto-generated code 
+enum Event {
+    Update,  // <2> Create three variants of Event, including one value for unrecognized events
+    Delete,  // <2>
+    Unknown, // <2>
+}
+
+type Message = String; // <3> A convenient name for String for use in this crate's context 
+
+fn parse_log(line: &'static str) -> (Event, Message) { // <4> A function for parsing a line and converting it into semi-structured data 
+  let parts: Vec<&str> = line.splitn(2, ' ').collect(); // <5> `collect()` consumes an iterator (returned from `line.splitn()`) and returns `Vec<T>`
+  if parts.len() == 1 {  // <6> If `line.splitn()` didn't split `log` into two parts, return an error 
+    return (Event::Unknown, String::from(line))
+  }
+
+  let event = parts[0];              // <7> Assign each part to a variable for ease of future use
+  let rest = String::from(parts[1]); // <7>
+
+  match event {  
+    "UPDATE" | "update" => (Event::Update, rest), // <8> When we match a known event, return structured data
+    "DELETE" | "delete" => (Event::Delete, rest), // <8>
+    _ => (Event::Unknown, String::from(line)), // <9> If we don't recognize the event type, return the whole line 
+  }
+}
+
+fn main() {
+  let log = "BEGIN Transaction XK342
+UPDATE 234:LS/32231 {\"price\": 31.00} -> {\"price\": 40.00}
+DELETE 342:LO/22111";
+
+  for line in log.lines(){
+    let parse_result = parse_log(line);
+    println!("{:?}", parse_result);
+  }
+}
\ No newline at end of file
-- 
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