diff --git a/src/eval.rs b/src/eval.rs
index bf6a826..cb1cb8b 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -1,14 +1,17 @@
-use std::collections::HashSet;
 use std::result;
 
 use chrono::{Datelike, NaiveDate};
 
-use crate::files::commands::{Birthday, Command, File, Note, Spec, Task};
+use crate::eval::entry::EntryDate;
+use crate::files::commands::{Birthday, Command};
+use crate::files::{Files, Source};
 
-use self::entries::{DateRange, Entry, EntryKind, EntryMap};
+use self::entry::{Entry, EntryKind, EntryMap};
+pub use self::range::DateRange;
 
 mod delta;
-pub mod entries;
+mod entry;
+mod range;
 
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
@@ -18,114 +21,85 @@ pub enum Error {
 
 type Result<T> = result::Result<T, Error>;
 
-fn eval_spec(spec: &Spec, index: usize, map: &mut EntryMap) -> Result<()> {
-    Ok(())
+struct Eval {
+    map: EntryMap,
+    source: Source,
 }
 
-fn eval_task(task: &Task, index: usize, range: DateRange) -> Result<Vec<Entry>> {
-    let mut map = EntryMap::new(range);
-
-    map.from = task.from;
-    map.until = task.until;
-
-    for date in &task.except {
-        map.block(*date);
+impl Eval {
+    pub fn new(range: DateRange, source: Source) -> Self {
+        Self {
+            map: EntryMap::new(range),
+            source,
+        }
     }
 
-    for spec in &task.when {
-        eval_spec(spec, index, &mut map)?;
-    }
+    fn eval_birthday(&mut self, birthday: &Birthday) {
+        for year in self.map.range().years() {
+            let when = &birthday.when;
+            let mut title = birthday.title.clone();
 
-    let done: HashSet<NaiveDate> = task
-        .done
-        .iter()
-        .filter_map(|done| done.refering_to)
-        .collect();
+            if when.year_known {
+                let age = year - when.date.year();
+                if age < 0 {
+                    continue;
+                }
+                title.push_str(&format!(" ({})", age));
+            }
 
-    for (date, entry) in map.map.iter_mut() {
-        if let Some(entry) = entry {
-            if done.contains(date) {
-                entry.kind.done();
+            if let Some(date) = when.date.with_year(year) {
+                let entry = Entry {
+                    kind: EntryKind::Birthday,
+                    title: title.clone(),
+                    desc: birthday.desc.clone(),
+                    source: self.source,
+                    date: EntryDate::Date { root: date },
+                };
+                self.map.insert(date, entry);
+            } else {
+                assert_eq!(when.date.month(), 2);
+                assert_eq!(when.date.day(), 29);
+                let date = NaiveDate::from_ymd(year, 2, 28);
+                let entry = Entry {
+                    kind: EntryKind::Birthday,
+                    title: format!("{} (first half)", title),
+                    desc: birthday.desc.clone(),
+                    source: self.source,
+                    date: EntryDate::Date { root: date },
+                };
+                self.map.insert(date, entry);
+
+                let date = NaiveDate::from_ymd(year, 3, 1);
+                let entry = Entry {
+                    kind: EntryKind::Birthday,
+                    title: format!("{} (second half)", title),
+                    desc: birthday.desc.clone(),
+                    source: self.source,
+                    date: EntryDate::Date { root: date },
+                };
+                self.map.insert(date, entry);
             }
         }
     }
 
-    Ok(map.drain())
-}
-
-fn eval_note(task: &Note, index: usize, range: DateRange) -> Result<Vec<Entry>> {
-    let mut map = EntryMap::new(range);
-
-    map.from = task.from;
-    map.until = task.until;
-
-    for date in &task.except {
-        map.block(*date);
-    }
-
-    for spec in &task.when {
-        eval_spec(spec, index, &mut map)?;
-    }
-
-    Ok(map.drain())
-}
-
-fn eval_birthday(bd: &Birthday, index: usize, range: DateRange) -> Result<Vec<Entry>> {
-    let mut map = EntryMap::new(range);
-
-    for year in range.years() {
-        if bd.when.year_known && year < bd.when.date.year() {
-            continue;
+    pub fn eval(&mut self, command: &Command) -> Result<Vec<Entry>> {
+        // This function fills the entry map and then drains it again, so in
+        // theory, the struct can even be reused afterwards.
+        match command {
+            Command::Task(task) => todo!(),
+            Command::Note(note) => todo!(),
+            Command::Birthday(birthday) => self.eval_birthday(birthday),
         }
+        Ok(self.map.drain())
+    }
+}
 
-        let title = if bd.when.year_known {
-            let age = year - bd.when.date.year();
-            format!("{} ({})", bd.title, age)
-        } else {
-            bd.title.to_string()
-        };
-
-        match bd.when.date.with_year(year) {
-            Some(date) => {
-                let mut entry = Entry::new(index, EntryKind::Birthday, title);
-                entry.start = Some(date);
-                map.insert(date, entry);
-            }
-            None => {
-                // We must've hit a non-leapyear
-                assert_eq!(bd.when.date.month(), 2);
-                assert_eq!(bd.when.date.day(), 29);
-
-                let first_date = NaiveDate::from_ymd(year, 2, 28);
-                let first_title = format!("{} (first half)", title);
-                let mut first_entry = Entry::new(index, EntryKind::Birthday, first_title);
-                first_entry.start = Some(first_date);
-                map.insert(first_date, first_entry);
-
-                let second_date = NaiveDate::from_ymd(year, 3, 1);
-                let second_title = format!("{} (second half)", title);
-                let mut second_entry = Entry::new(index, EntryKind::Birthday, second_title);
-                second_entry.start = Some(second_date);
-                map.insert(second_date, second_entry);
-            }
+impl Files {
+    pub fn eval(&self, range: DateRange) -> Result<Vec<Entry>> {
+        let mut result = vec![];
+        for command in self.commands() {
+            result.append(&mut Eval::new(range, command.source).eval(command.command)?);
         }
-    }
-
-    Ok(map.drain())
-}
-
-fn eval_command(command: &Command, index: usize, range: DateRange) -> Result<Vec<Entry>> {
-    match command {
-        Command::Task(task) => eval_task(task, index, range),
-        Command::Note(note) => eval_note(note, index, range),
-        Command::Birthday(birthday) => eval_birthday(birthday, index, range),
+        Ok(result)
     }
 }
-
-pub fn eval(file: &File, range: DateRange) -> Result<Vec<Entry>> {
-    let mut result = vec![];
-    for (index, command) in file.commands.iter().enumerate() {
-        result.append(&mut eval_command(command, index, range)?);
-    }
-    Ok(result)
-}
diff --git a/src/eval/entries.rs b/src/eval/entries.rs
deleted file mode 100644
index 4b3b434..0000000
--- a/src/eval/entries.rs
+++ /dev/null
@@ -1,99 +0,0 @@
-use std::collections::HashMap;
-use std::ops::RangeInclusive;
-
-use chrono::{Datelike, NaiveDate};
-
-use crate::files::commands::Time;
-
-#[derive(Debug, PartialEq, Eq)]
-pub enum EntryKind {
-    Task,
-    DoneTask,
-    Note,
-    Birthday,
-}
-
-impl EntryKind {
-    pub fn done(&mut self) {
-        if matches!(self, Self::Task) {
-            *self = Self::DoneTask;
-        }
-    }
-}
-
-#[derive(Debug)]
-pub struct Entry {
-    pub kind: EntryKind,
-    pub title: String,
-    pub desc: Vec<String>,
-
-    /// Index in the source file
-    pub source: usize,
-
-    pub start: Option<NaiveDate>,
-    pub start_time: Option<Time>,
-    pub end: Option<NaiveDate>,
-    pub end_time: Option<Time>,
-}
-
-impl Entry {
-    pub fn new(source: usize, kind: EntryKind, title: String) -> Self {
-        Self {
-            kind,
-            title,
-            desc: vec![],
-            source,
-            start: None,
-            start_time: None,
-            end: None,
-            end_time: None,
-        }
-    }
-}
-
-#[derive(Debug, Clone, Copy)]
-pub struct DateRange {
-    pub from: NaiveDate,
-    pub until: NaiveDate,
-}
-
-impl DateRange {
-    pub fn new(from: NaiveDate, until: NaiveDate) -> Self {
-        assert!(from <= until);
-        Self { from, until }
-    }
-
-    pub fn years(&self) -> RangeInclusive<i32> {
-        self.from.year()..=self.until.year()
-    }
-}
-
-pub struct EntryMap {
-    pub range: DateRange,
-    pub from: Option<NaiveDate>,
-    pub until: Option<NaiveDate>,
-    pub map: HashMap<NaiveDate, Option<Entry>>,
-}
-
-impl EntryMap {
-    pub fn new(range: DateRange) -> Self {
-        Self {
-            range,
-            from: None,
-            until: None,
-            map: HashMap::new(),
-        }
-    }
-
-    pub fn block(&mut self, date: NaiveDate) {
-        self.map.entry(date).or_insert(None);
-    }
-
-    pub fn insert(&mut self, date: NaiveDate, entry: Entry) {
-        self.map.entry(date).or_insert(Some(entry));
-    }
-
-    pub fn drain(&mut self) -> Vec<Entry> {
-        self.map.drain().filter_map(|(_, entry)| entry).collect()
-    }
-}
diff --git a/src/eval/entry.rs b/src/eval/entry.rs
new file mode 100644
index 0000000..7b3ac9f
--- /dev/null
+++ b/src/eval/entry.rs
@@ -0,0 +1,94 @@
+use std::collections::HashMap;
+
+use chrono::NaiveDate;
+
+use crate::files::commands::Time;
+use crate::files::Source;
+
+use super::range::DateRange;
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum EntryKind {
+    Task,
+    DoneTask,
+    Note,
+    Birthday,
+}
+
+#[derive(Debug)]
+pub enum EntryDate {
+    None,
+    Date {
+        root: NaiveDate,
+    },
+    DateWithTime {
+        root: NaiveDate,
+        root_time: Time,
+    },
+    DateToDate {
+        root: NaiveDate,
+        other: NaiveDate,
+    },
+    DateToDateWithTime {
+        root: NaiveDate,
+        root_time: Time,
+        other: NaiveDate,
+        other_time: Time,
+    },
+}
+
+impl EntryDate {
+    pub fn root(&self) -> Option<NaiveDate> {
+        match self {
+            EntryDate::None => None,
+            EntryDate::Date { root, .. } => Some(*root),
+            EntryDate::DateWithTime { root, .. } => Some(*root),
+            EntryDate::DateToDate { root, .. } => Some(*root),
+            EntryDate::DateToDateWithTime { root, .. } => Some(*root),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Entry {
+    pub kind: EntryKind,
+    pub title: String,
+    pub desc: Vec<String>,
+
+    pub source: Source,
+    pub date: EntryDate,
+}
+
+pub struct EntryMap {
+    range: DateRange,
+    map: HashMap<NaiveDate, Option<Entry>>,
+}
+
+impl EntryMap {
+    pub fn new(range: DateRange) -> Self {
+        Self {
+            range,
+            map: HashMap::new(),
+        }
+    }
+
+    pub fn range(&self) -> DateRange {
+        self.range
+    }
+
+    pub fn block(&mut self, date: NaiveDate) {
+        if self.range.contains(date) {
+            self.map.entry(date).or_insert(None);
+        }
+    }
+
+    pub fn insert(&mut self, date: NaiveDate, entry: Entry) {
+        if self.range.contains(date) {
+            self.map.entry(date).or_insert(Some(entry));
+        }
+    }
+
+    pub fn drain(&mut self) -> Vec<Entry> {
+        self.map.drain().filter_map(|(_, entry)| entry).collect()
+    }
+}
diff --git a/src/eval/range.rs b/src/eval/range.rs
new file mode 100644
index 0000000..9801a94
--- /dev/null
+++ b/src/eval/range.rs
@@ -0,0 +1,32 @@
+use std::ops::RangeInclusive;
+
+use chrono::{Datelike, NaiveDate};
+
+#[derive(Debug, Clone, Copy)]
+pub struct DateRange {
+    from: NaiveDate,
+    until: NaiveDate,
+}
+
+impl DateRange {
+    pub fn new(from: NaiveDate, until: NaiveDate) -> Self {
+        assert!(from <= until);
+        Self { from, until }
+    }
+
+    pub fn contains(&self, date: NaiveDate) -> bool {
+        self.from <= date && date <= self.until
+    }
+
+    pub fn from(&self) -> NaiveDate {
+        self.from
+    }
+
+    pub fn until(&self) -> NaiveDate {
+        self.until
+    }
+
+    pub fn years(&self) -> RangeInclusive<i32> {
+        self.from.year()..=self.until.year()
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 5336b74..6fd540a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,8 +5,10 @@
 
 use std::path::PathBuf;
 
+use chrono::NaiveDate;
 use structopt::StructOpt;
 
+use crate::eval::DateRange;
 use crate::files::Files;
 
 mod eval;
@@ -24,6 +26,12 @@ fn main() -> anyhow::Result<()> {
     let mut files = Files::load(&opt.file)?;
     println!("{}", files.now().format("%F %T %Z"));
 
+    let range = DateRange::new(
+        NaiveDate::from_ymd(2021, 11, 20),
+        NaiveDate::from_ymd(2021, 11, 26),
+    );
+    println!("{:#?}", files.eval(range));
+
     files.mark_all_dirty();
     files.save()?;