From: Harishankar <v.harishankar@gmail.com>
Date: Sun, 31 May 2020 07:18:40 +0000 (+0530)
Subject: Readme added
X-Git-Tag: 0.1-a~1
X-Git-Url: https://harishankar.org/repos/?a=commitdiff_plain;h=0445377869901378c214185334ca4cbd1b900396;p=evpf.git

Readme added
Added a Readme file
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+# evpf - postfix evaluator
+
+evpf (**ev**aluate **p**ost**f**ix is a simple postfix expression evaluator
+written as a learning project in rust. It supports both command line and 
+interactive mode.
+
+## Command line mode
+
+    evpf <expression>
+
+where `<expression>` is a postfix expression like `20 30 + 11 -` etc. 
+Currently only 4 operators are supported: `+`, `-`, `*` and `/`. (In command
+line mode, `*` has to be escaped using `\*` to work properly.)
+
+## Interactive mode
+
+Interactive mode displays a prompt where expressions can be evaluated by 
+typing into the prompt (line editing and session-history supported by 
+`rustyline`. 
+
+    evpf> 
+
+In interactive mode, apart from entering expressions, the following commands 
+are supported
+
+* `q` or `Q` - quit
+* `?` or `h` or `H` - help
+