X-Git-Url: https://harishankar.org/repos/?p=evpf.git;a=blobdiff_plain;f=src%2Fmain.rs;h=d2371937b73204e75fae8da3dc96fba43fbc461e;hp=bab1e521d17a5e4f2e794d645f851c2b448c0d01;hb=e12e35ce57fb851e14e6589959c622512a9d1091;hpb=ac6c2056e35e042ada5f88580329bc2ca51e72ff

diff --git a/src/main.rs b/src/main.rs
index bab1e52..d237193 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,8 +1,8 @@
 use std::io;
 use std::io::Write;
 use regex::Regex;
-use ansi_term::Colour;
-use ansi_term::Style;
+use colored::*;
+use std::env;
 
 const ILLEGAL_EXP : &'static str = "Illegal Expression";
 const ERR_PARSING_NOT_MATCH : &'static str = "Error parsing expression! \
@@ -11,13 +11,12 @@ 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 an expression in postfix style to evaluate.",
+				["Type a postfix expression to evaluate.",
 				 "Example: 4 5 + 12 -",
 				 "Supported operators: +, -, *, /",
 				 "Type q, Q to quit"
 				 ];
 
-const RESULT : &'static str = "Result";
 const ERROR : &'static str = "Error";
 const ERROR_HELP : &'static str = "Type ? or h or H for help";
 
@@ -133,15 +132,43 @@ fn evaluate (expr : &str, match_num : &regex::Regex) -> Result<f32,String> {
 	}
 }
 
-fn main() {
+// Single command mode - command line arguments mode - evaluate the expression
+// given in the command line and quit
+fn run_command_line (args : &Vec<String>, match_num : &regex::Regex) {
+	let mut expr = String::new ();
+	let mut i = 0;
+	// create the expression string to evaluate
+	for arg in args.iter() {
+		if i > 0 {
+			expr.push_str (&arg);
+			expr.push_str (" ");
+		}
+		i += 1;
+	}
+	// evaluate the result 
+	let res = evaluate (&expr, &match_num);
+	// if Result is OK then print the result in green
+	if res.is_ok () {
+		let restxt = format! ("{}", res.unwrap());
+		println! ("{}", restxt.green ());
+	} else {
+	// print the error in purple
+		let errtxt = format! ("{}: {}", ERROR, 
+										res.unwrap_err());
+		eprintln! ("{}", errtxt.purple ());
+	}
+}
+
+// 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 ();
-	// regular expression to match a number 
-	let match_num = Regex::new (r"^\d+?\.*?\d*?$").unwrap ();
+
 	// loop until a blank line is received	
 	loop {
 		expr.clear ();	
-		print!("{}", Style::new().bold().paint("evpf>"));
+		print!("{}", "evpf>".bold() );
 		io::stdout().flush ().expect (ERR_FLUSHING);
 		// read a line of text
 		io::stdin().read_line (&mut expr).expect (ERR_READING_LINE);
@@ -154,7 +181,7 @@ fn main() {
 		} else if expr == "?" || expr == "h" || expr == "H" {
 		// display help text
 			for text in HELP_TEXT.iter() {
-				println! ("{}", Colour::Cyan.paint(*text));
+				println! ("{}", text.cyan() );
 			}
 
 			continue;
@@ -168,15 +195,34 @@ fn main() {
 		
 		// if Result is OK then print the result in green
 		if res.is_ok () {
-			let restxt = format! ("{}: {}", RESULT, 
-											res.unwrap());
-			println! ("{}", Colour::Green.paint (restxt));
+			let restxt = format! ("{}", res.unwrap());
+			println! ("{}", restxt.green ());
 		} else {
 		// print the error in purple
 			let errtxt = format! ("{}: {}", ERROR, 
 											res.unwrap_err());
-			eprintln! ("{}", Colour::Purple.paint (errtxt));
-			eprintln! ("{}", Colour::Purple.paint (ERROR_HELP));
+			eprintln! ("{}", errtxt.purple());
+			eprintln! ("{}", ERROR_HELP.purple());
 		}
 	}
 }
+
+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 ();
+	
+	if args.len () > 1 {
+	// if arguments are provided run in command line mode - i.e. print the 
+	// result and exit	
+		run_command_line (&args, &match_num);
+		
+	} else {
+		// if arguments are not provided run in interactive mode - 
+		// display a prompt and get the expression 
+		// repeat until the user quits
+		run_interactive_mode (&match_num);
+
+	}
+}