Start reorganizing code by creating files module

src/files.rs

@@ -0,0 +1,59 @@
+use std::collections::HashMap;
+use std::path::{Path, PathBuf};
+use std::{fs, io, result};
+
+use chrono_tz::Tz;
+
+use crate::commands::File;
+use crate::parse;
+
+#[derive(Debug)]
+pub struct Files {
+    files: HashMap<PathBuf, File>,
+    timezone: Option<Tz>,
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("{0}")]
+    IoError(#[from] io::Error),
+    #[error("{0}")]
+    ParseError(#[from] parse::Error),
+}
+
+pub type Result<T> = result::Result<T, Error>;
+
+impl Files {
+    pub fn load(path: &Path) -> Result<Self> {
+        let mut new = Self {
+            files: HashMap::new(),
+            timezone: None,
+        };
+
+        new.load_file(path)?;
+        new.determine_timezone()?;
+
+        Ok(new)
+    }
+
+    fn load_file(&mut self, path: &Path) -> Result<()> {
+        let canon_path = path.canonicalize()?;
+        if self.files.contains_key(&canon_path) {
+            // We've already loaded this exact file.
+            return Ok(());
+        }
+
+        let content = fs::read_to_string(path)?;
+        let file = parse::parse(path, &content)?;
+        self.files.insert(canon_path, file);
+
+        // TODO Also load all imported files
+
+        Ok(())
+    }
+
+    fn determine_timezone(&mut self) -> Result<()> {
+        // TODO Implement once files can specify time zones
+        Ok(())
+    }
+}

src/main.rs

@@ -1,13 +1,12 @@
-use std::fs;
 use std::path::PathBuf;
 
-use chrono::NaiveDate;
 use structopt::StructOpt;
 
-use crate::eval::entries::DateRange;
+use crate::files::Files;
 
 mod commands;
 mod eval;
+mod files;
 mod format;
 mod parse;
 
@@ -19,15 +18,7 @@ pub struct Opt {
 
 fn main() -> anyhow::Result<()> {
     let opt = Opt::from_args();
-    let content = fs::read_to_string(&opt.file)?;
-    let file = parse::parse(&opt.file, &content)?;
-    let entries = eval::eval(
-        &file,
-        DateRange::new(
-            NaiveDate::from_ymd(2021, 1, 1),
-            NaiveDate::from_ymd(2021, 12, 31),
-        ),
-    )?;
-    println!("{:#?}", entries);
+    let files = Files::load(&opt.file)?;
+    println!("{:#?}", files);
     Ok(())
 }

src/parse.rs

@@ -2,7 +2,7 @@ use std::path::Path;
 use std::result;
 
 use chrono::NaiveDate;
-use pest::error::{Error, ErrorVariant};
+use pest::error::ErrorVariant;
 use pest::iterators::Pair;
 use pest::prec_climber::{Assoc, Operator, PrecClimber};
 use pest::{Parser, Span};
@@ -16,9 +16,10 @@ use crate::commands::{
 #[grammar = "parse/todayfile.pest"]
 struct TodayfileParser;
 
-type Result<T> = result::Result<T, Error<Rule>>;
+pub type Error = pest::error::Error<Rule>;
+pub type Result<T> = result::Result<T, Error>;
 
-fn error<S: Into<String>>(span: Span, message: S) -> Error<Rule> {
+fn error<S: Into<String>>(span: Span, message: S) -> Error {
     Error::new_from_span(
         ErrorVariant::CustomError {
             message: message.into(),