Add a fake io reader to test lexing #56

src/lib.rs

@@ -9,6 +9,7 @@ extern crate derive_new;
 pub mod mango {
     // Utilities
     pub mod cli;
+    pub mod io;
     pub mod jit;
     pub mod util;
 

src/mango/io/fortest/fromstr.rs

@@ -0,0 +1,29 @@
+use mango::io::typ::Reader;
+use regex::Regex;
+
+/// Implementation of [Reader] that reads from a pre-provided string.
+/// Mostly for testing purposes.
+pub struct StringReader {
+    code: String,
+    index: usize,
+}
+
+impl StringReader {
+    pub fn new(code: String) -> Self {
+        StringReader { code, index: 0 }
+    }
+}
+
+impl Reader for StringReader {
+    fn equals(&mut self, text: &str) -> bool {
+        if &self.code[self.index..self.index + text.len()] == text {
+            self.index += text.len();
+            return true;
+        }
+        false
+    }
+
+    fn matches(&mut self, pattern: Regex) -> Option<String> {
+        unimplemented!() // TODO
+    }
+}

src/mango/io/fortest/mod.rs

@@ -0,0 +1,2 @@
+pub mod fromstr;
+pub use self::fromstr::*;

src/mango/io/mod.rs

@@ -0,0 +1,3 @@
+pub mod typ;
+
+pub mod fortest;

src/mango/io/typ.rs

@@ -0,0 +1,14 @@
+use regex::Regex;
+
+/// A reader represents a source 'file', which may be a file, webpage, string, ...
+pub trait Reader {
+    /// Checks whether the `text` is found starting from the current position.
+    fn equals(&mut self, text: &str) -> bool;
+
+    /// Checks whether the code from the current position matches a regex pattern.
+    fn matches(&mut self, pattern: Regex) -> Option<String>;
+}
+
+pub trait Writer {
+    // TODO
+}