Minor error handling fixed

[evpf.git] / src / main.rs

diff --git a/src/main.rs b/src/main.rs
index d237193..51ea94e 100644 (file)
--- 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 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 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 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";
 
 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 ();
 
 // 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 {
        // 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 
 
                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());
                }
        }
                        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 
 }
 
 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 
        
        if args.len () > 1 {
        // if arguments are provided run in command line mode - i.e. print the