updated code

chapter2/Cargo.lock

@@ -0,0 +1,5 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "ocalc"
+version = "1.0.0"

chapter2/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "ocalc"
+version = "1.0.0"
+authors = ["peshwar9"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

chapter2/src/main.rs

@@ -0,0 +1,48 @@
+/// This is the main command-line application for arithmetic expression evaluator
+
+// Standard library
+use std::f64;
+use std::io;
+
+// code for arithmetic expression evaluation is in parsemath module
+mod parsemath;
+use parsemath::parser::ParseError;
+
+
+// Function to invoke Parser and evaluate expression
+fn evaluate(expr: String) -> Result<f64, ParseError> {
+    let len = expr.len();
+    let mut expr = expr;
+    expr.truncate(len - 1); // remove newline character
+    let mut math_parser = parsemath::parser::Parser::new(&expr)?;
+    let ast = math_parser.parse()?;
+    println!("The generated AST is {:?}", ast);
+
+    Ok(parsemath::ast::eval(ast)?)
+}
+
+// Main function reads aritnmetic expression from command-line and displays result and error.
+// It calls the evaluate function to perform compuation.
+
+fn main() {
+    println!("Hello! Welcome to Arithmetic expression evaluator.");
+    println!("You can calculate value for expression such as 2*3+(4-5)+2^3/4. ");
+    println!("Allowed numbers: positive, negative and decimals.");
+    println!("Supported operations: Add, Subtract, Multiply, Divide, PowerOf(^). ");
+    println!("Enter your arithmetic expression below:");
+    loop {
+        let mut input = String::new();
+        match io::stdin().read_line(&mut input) {
+            Ok(_) => {
+                match evaluate(input) {
+                    Ok(val) => println!("The computed number is {}\n", val),
+                    Err(_) => {
+                        println!("Error in evaluating expression. Please enter valid expression\n");
+                    }
+                };
+            }
+
+            Err(error) => println!("error: {}", error),
+        }
+    }
+}

chapter2/src/parsemath/parser.rs

@@ -1,6 +1,5 @@
 /// This program reads tokens returned by Tokenizer and converts them into AST.
 // Standard lib
-use std::error;
 use std::fmt;
 
 // Internal modules
@@ -172,16 +171,16 @@ impl fmt::Display for ParseError {
     }
 }
 
-impl error::Error for ParseError {
+/*impl error::Error for ParseError {
     fn description(&self) -> &str {
         match &self {
             self::ParseError::UnableToParse(e) => &e,
             self::ParseError::InvalidOperator(e) => &e,
         }
     }
-}
+}*/
 
-// Handle error thrown from Tokenizer
+// Handle error thrown from AST module
 
 impl std::convert::From<std::boxed::Box<dyn std::error::Error>> for ParseError {
     fn from(_evalerr: std::boxed::Box<dyn std::error::Error>) -> Self {

chapter2/target/rls/.rustc_info.json

@@ -0,0 +1 @@
+{"rustc_fingerprint":4503571881771466578,"outputs":{"1164083562126845933":["rustc 1.43.0 (4fb7144ed 2020-04-20)\nbinary: rustc\ncommit-hash: 4fb7144ed159f94491249e86d5bbd033b5d60550\ncommit-date: 2020-04-20\nhost: x86_64-apple-darwin\nrelease: 1.43.0\nLLVM version: 9.0\n",""],"4476964694761187371":["___\nlib___.rlib\nlib___.dylib\nlib___.dylib\nlib___.a\nlib___.dylib\n/Users/prabhueshwarla/.rustup/toolchains/stable-x86_64-apple-darwin\ndebug_assertions\nproc_macro\ntarget_arch=\"x86_64\"\ntarget_endian=\"little\"\ntarget_env=\"\"\ntarget_family=\"unix\"\ntarget_feature=\"fxsr\"\ntarget_feature=\"sse\"\ntarget_feature=\"sse2\"\ntarget_feature=\"sse3\"\ntarget_feature=\"ssse3\"\ntarget_os=\"macos\"\ntarget_pointer_width=\"64\"\ntarget_vendor=\"apple\"\nunix\n",""]},"successes":{}}

chapter2/target/rls/debug/.fingerprint/ocalc-628cd1d3b6bbee1e/invoked.timestamp

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+This file has an mtime of when this was started.

chapter2/target/rls/debug/.fingerprint/ocalc-628cd1d3b6bbee1e/test-bin-ocalc-628cd1d3b6bbee1e

@@ -0,0 +1 @@
+bc1679c1c2047cad

chapter2/target/rls/debug/.fingerprint/ocalc-628cd1d3b6bbee1e/test-bin-ocalc-628cd1d3b6bbee1e.json

@@ -0,0 +1 @@
+{"rustc":12217307662193597186,"features":"[]","target":7786015957388683530,"profile":1647870076477133176,"path":1036222786711178230,"deps":[],"local":[{"CheckDepInfo":{"dep_info":"debug/.fingerprint/ocalc-628cd1d3b6bbee1e/dep-test-bin-ocalc-628cd1d3b6bbee1e"}}],"rustflags":[],"metadata":13779719443416291531}

chapter2/target/rls/debug/.fingerprint/ocalc-9bb38f3499aac79e/bin-ocalc-9bb38f3499aac79e

@@ -0,0 +1 @@
+084a8cc2b1018ce0

chapter2/target/rls/debug/.fingerprint/ocalc-9bb38f3499aac79e/bin-ocalc-9bb38f3499aac79e.json

@@ -0,0 +1 @@
+{"rustc":12217307662193597186,"features":"[]","target":7786015957388683530,"profile":14891217944882224483,"path":1036222786711178230,"deps":[],"local":[{"CheckDepInfo":{"dep_info":"debug/.fingerprint/ocalc-9bb38f3499aac79e/dep-bin-ocalc-9bb38f3499aac79e"}}],"rustflags":[],"metadata":13779719443416291531}

chapter2/target/rls/debug/.fingerprint/ocalc-9bb38f3499aac79e/invoked.timestamp

@@ -0,0 +1 @@
+This file has an mtime of when this was started.

chapter2/target/rls/debug/deps/ocalc-628cd1d3b6bbee1e.d

@@ -0,0 +1,10 @@
+/Users/prabhueshwarla/rust/learn/commandline/ocalc/target/rls/debug/deps/ocalc-628cd1d3b6bbee1e.rmeta: src/main.rs src/parsemath/mod.rs src/parsemath/ast.rs src/parsemath/parser.rs src/parsemath/token.rs src/parsemath/tokenizer.rs
+
+/Users/prabhueshwarla/rust/learn/commandline/ocalc/target/rls/debug/deps/ocalc-628cd1d3b6bbee1e.d: src/main.rs src/parsemath/mod.rs src/parsemath/ast.rs src/parsemath/parser.rs src/parsemath/token.rs src/parsemath/tokenizer.rs
+
+src/main.rs:
+src/parsemath/mod.rs:
+src/parsemath/ast.rs:
+src/parsemath/parser.rs:
+src/parsemath/token.rs:
+src/parsemath/tokenizer.rs:

chapter2/target/rls/debug/deps/ocalc-9bb38f3499aac79e.d

@@ -0,0 +1,10 @@
+/Users/prabhueshwarla/rust/learn/commandline/ocalc/target/rls/debug/deps/ocalc-9bb38f3499aac79e.rmeta: src/main.rs src/parsemath/mod.rs src/parsemath/ast.rs src/parsemath/parser.rs src/parsemath/token.rs src/parsemath/tokenizer.rs
+
+/Users/prabhueshwarla/rust/learn/commandline/ocalc/target/rls/debug/deps/ocalc-9bb38f3499aac79e.d: src/main.rs src/parsemath/mod.rs src/parsemath/ast.rs src/parsemath/parser.rs src/parsemath/token.rs src/parsemath/tokenizer.rs
+
+src/main.rs:
+src/parsemath/mod.rs:
+src/parsemath/ast.rs:
+src/parsemath/parser.rs:
+src/parsemath/token.rs:
+src/parsemath/tokenizer.rs: