X-Git-Url: https://harishankar.org/repos/?p=evpf.git;a=blobdiff_plain;f=src%2Fmain.rs;h=51ea94eb5e681337e5b6ecb386c8f81771fcb528;hp=d2371937b73204e75fae8da3dc96fba43fbc461e;hb=HEAD;hpb=e12e35ce57fb851e14e6589959c622512a9d1091

diff --git a/src/main.rs b/src/main.rs
index d237193..51ea94e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,21 +1,26 @@
-use std::io;
-use std::io::Write;
 use regex::Regex;
 use colored::*;
 use std::env;
+use rustyline::Editor;
+use std::path::PathBuf;
 
 const ILLEGAL_EXP : &'static str = "Illegal Expression";
 const ERR_PARSING_NOT_MATCH : &'static str = "Error parsing expression! \
 				 Must be a number or operator (+,-,* or /)";
 const ERR_POSTFIX_INCOMPLETE : &'static str = "Postfix expression incomplete!";
-const ERR_FLUSHING : &'static str = "Error flushing!";
-const ERR_READING_LINE : &'static str = "Error reading line!";
 const HELP_TEXT : [&str ; 4] = 
 				["Type a postfix expression to evaluate.",
 				 "Example: 4 5 + 12 -",
 				 "Supported operators: +, -, *, /",
 				 "Type q, Q to quit"
 				 ];
+				 
+const HOMEDIR_NOT_FOUND : &'static str = "User home directory not found \
+				(missing environment?).";
+				
+const HISTORY_FILE_NOT_FOUND : &'static str = "History file not found.";
+
+const SAVE_HISTORY_ERROR : &'static str = "Unable to save command history!";
 
 const ERROR : &'static str = "Error";
 const ERROR_HELP : &'static str = "Type ? or h or H for help";
@@ -159,21 +164,59 @@ fn run_command_line (args : &Vec<String>, match_num : &regex::Regex) {
 	}
 }
 
+// get the history file name as string - home dir + .evpfhistory
+fn get_history_file () -> Result<String,String> {
+	// get the environment variable HOME
+	let home_path = env::var ("HOME");
+	// if not found, return an error
+	if home_path.is_err () {
+		return Err (HOMEDIR_NOT_FOUND.to_string());
+	}
+	// build the path for the history file i.e. homedir + .evpfhistory in
+	// platform independent way
+	let mut hist_file = PathBuf::new ();
+	hist_file.push (home_path.unwrap());
+	hist_file.push (".evpfhistory");	
+	
+	// if cannot convert to string return error 
+	if hist_file.to_str ().is_none () {
+		return Err (HOMEDIR_NOT_FOUND.to_string());
+	}
+	
+	// return the history file path as a string
+	let hist_file_path = String::from (hist_file.to_str().unwrap());
+	return Ok (hist_file_path);
+}
+
 // Interactive mode - display the prompt and evaluate expressions entered into
 // the prompt - until user quits
 fn run_interactive_mode (match_num : &regex::Regex) {
 	// get a line from input and evaluate it 
 	let mut expr = String::new ();
 
+	let mut rl = Editor::<()>::new ();
+	
+	// load the history file
+	let hist_file = get_history_file ();
+	// if unable to load the history file, display the appropriate error
+	if hist_file.is_err () {
+		eprintln! ("{}", &hist_file.unwrap_err());
+	} else {
+		if rl.load_history (&hist_file.unwrap ()).is_err () {
+			eprintln! ("{}", HISTORY_FILE_NOT_FOUND.purple());
+		}
+	}
 	// loop until a blank line is received	
 	loop {
-		expr.clear ();	
-		print!("{}", "evpf>".bold() );
-		io::stdout().flush ().expect (ERR_FLUSHING);
-		// read a line of text
-		io::stdin().read_line (&mut expr).expect (ERR_READING_LINE);
-		// trim the text
-		let expr = expr.trim ();
+		expr.clear ();
+		
+		let line = rl.readline ("evpf> ");
+		if line.is_err () {
+			break;
+		}
+		let hist = line.unwrap ();
+		rl.add_history_entry (&hist);
+		expr.push_str (&hist);
 
 		if expr == "q" || expr == "Q" {
 		// quit if the expression is q or Qs 
@@ -205,13 +248,22 @@ fn run_interactive_mode (match_num : &regex::Regex) {
 			eprintln! ("{}", ERROR_HELP.purple());
 		}
 	}
+	// save the history 
+	let hist_file = get_history_file ();
+	if ! hist_file.is_err () {
+		if rl.save_history (&hist_file.unwrap()).is_err () {
+			eprintln! ("{}", SAVE_HISTORY_ERROR);
+		}
+	} else {
+		eprintln! ("{}", &hist_file.unwrap_err());
+	}
 }
 
 fn main() {
 	// collect the command line arguments - if any 
 	let args : Vec<String> = env::args().collect ();
 	// regular expression to match a number 
-	let match_num = Regex::new (r"^\d+?\.*?\d*?$").unwrap ();
+	let match_num = Regex::new (r"^\-?\d+?\.*?\d*?$").unwrap ();
 	
 	if args.len () > 1 {
 	// if arguments are provided run in command line mode - i.e. print the