feat: add preprocessing function

Cargo.lock

@@ -2,6 +2,15 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "aho-corasick"
+version = "0.7.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cc936419f96fa211c1b9166887b38e5e40b19958e5b895be7c1f93adec7071ac"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -243,6 +252,7 @@ dependencies = [
  "dirs",
  "gethostname",
  "once_cell",
+ "regex",
  "rustyline",
  "shlex",
 ]
@@ -295,6 +305,23 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "regex"
+version = "1.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "48aaa5748ba571fb95cd2c85c09f629215d3a6ece942baa100950af03a34f733"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.6.28"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "456c603be3e8d448b072f410900c09faf164fbce2d480456f50eea6e25f9c848"
+
 [[package]]
 name = "rustix"
 version = "0.36.6"

Cargo.toml

@@ -9,5 +9,6 @@ ctrlc = "3.2"
 dirs = "4.0"
 gethostname = "0.4"
 once_cell = "1.17"
+regex = "1.7"
 rustyline = "10.1.0"
 shlex = "1.1"

src/execute.rs

@@ -6,12 +6,15 @@ use std::{io, thread};
 use crate::builtins::{execute_builtin, is_builtin, BuiltinConfig};
 use crate::error::ShellError;
 use crate::parse::parse_line;
+use crate::preprocess::preprocess;
 
 pub fn interpret(
-    line: String,
+    mut line: String,
     config: &mut BuiltinConfig,
     ctrlc_recv: Receiver<()>,
 ) -> Result<(), ShellError> {
+    line = preprocess(line)?;
+
     if line.is_empty() {
         return Err(ShellError::EmptyLine);
     }

src/main.rs

@@ -2,6 +2,7 @@ mod builtins;
 mod error;
 mod execute;
 mod parse;
+mod preprocess;
 mod prompt;
 
 use crate::builtins::BuiltinConfig;

src/preprocess.rs

@@ -0,0 +1,21 @@
+use crate::error::ShellError;
+use once_cell::unsync::Lazy;
+use regex::Regex;
+use std::env;
+
+const ENV_SET: Lazy<Regex> = Lazy::new(|| Regex::new(r#"(?P<key>\w+)=(?P<value>\w*)"#).unwrap());
+
+pub fn preprocess(line: String) -> Result<String, ShellError> {
+    if let Some(capture) = ENV_SET.captures(&line) {
+        let Some(key) = capture.name("key") else {
+            return Err(ShellError::MalformedArgs("cannot find key to set env variable".to_string()))
+        };
+        let value = capture
+            .name("value")
+            .map_or("".to_string(), |v| v.as_str().to_string());
+
+        env::set_var(key.as_str(), value)
+    }
+
+    Ok(line)
+}