From 1170009b4f39b3936e3a1eb0b220ee713fe3f70a Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Mon, 29 Nov 2021 11:14:48 +0000
Subject: [PATCH] Carry source spans for error messages

---
 src/eval/date_spec.rs    |  6 ++-
 src/eval/delta.rs        | 14 ++++---
 src/eval/formula_spec.rs | 18 ++++++---
 src/files/commands.rs    | 56 +++++++++++++++++++++++---
 src/files/format.rs      | 10 ++++-
 src/files/parse.rs       | 87 ++++++++++++++++++++++------------------
 6 files changed, 132 insertions(+), 59 deletions(-)

diff --git a/src/eval/date_spec.rs b/src/eval/date_spec.rs
index db8871d..377afb4 100644
--- a/src/eval/date_spec.rs
+++ b/src/eval/date_spec.rs
@@ -1,6 +1,6 @@
 use chrono::NaiveDate;
 
-use crate::files::commands::{self, DoneDate, Time};
+use crate::files::commands::{self, DoneDate, Spanned, Time};
 use crate::files::Source;
 
 use super::delta::{Delta, DeltaStep};
@@ -29,7 +29,9 @@ impl From<&commands::DateSpec> for DateSpec {
             .map(|delta| delta.into())
             .unwrap_or_default();
         if let Some(time) = spec.end_time {
-            end_delta.steps.push(DeltaStep::Time(time));
+            end_delta
+                .steps
+                .push(Spanned::new(time.span, DeltaStep::Time(time.value)));
         }
 
         let repeat: Option<Delta> = spec.repeat.as_ref().map(|repeat| (&repeat.delta).into());
diff --git a/src/eval/delta.rs b/src/eval/delta.rs
index f9ddc05..0080074 100644
--- a/src/eval/delta.rs
+++ b/src/eval/delta.rs
@@ -1,6 +1,6 @@
 use std::cmp::Ordering;
 
-use crate::files::commands::{self, Time, Weekday};
+use crate::files::commands::{self, Spanned, Time, Weekday};
 
 /// Like [`commands::DeltaStep`] but includes a new constructor,
 /// [`DeltaStep::Time`].
@@ -122,23 +122,27 @@ impl DeltaStep {
 
 #[derive(Debug, Default)]
 pub struct Delta {
-    pub steps: Vec<DeltaStep>,
+    pub steps: Vec<Spanned<DeltaStep>>,
 }
 
 impl From<&commands::Delta> for Delta {
     fn from(delta: &commands::Delta) -> Self {
         Self {
-            steps: delta.0.iter().map(|&step| step.into()).collect(),
+            steps: delta
+                .0
+                .iter()
+                .map(|step| Spanned::new(step.span, step.value.into()))
+                .collect(),
         }
     }
 }
 
 impl Delta {
     pub fn lower_bound(&self) -> i32 {
-        self.steps.iter().map(DeltaStep::lower_bound).sum()
+        self.steps.iter().map(|step| step.value.lower_bound()).sum()
     }
 
     pub fn upper_bound(&self) -> i32 {
-        self.steps.iter().map(DeltaStep::upper_bound).sum()
+        self.steps.iter().map(|step| step.value.upper_bound()).sum()
     }
 }
diff --git a/src/eval/formula_spec.rs b/src/eval/formula_spec.rs
index 3660a70..7321b2f 100644
--- a/src/eval/formula_spec.rs
+++ b/src/eval/formula_spec.rs
@@ -1,4 +1,4 @@
-use crate::files::commands::{self, DoneDate, Expr, Time, Var};
+use crate::files::commands::{self, DoneDate, Expr, Spanned, Time, Var};
 use crate::files::Source;
 
 use super::delta::{Delta, DeltaStep};
@@ -28,7 +28,9 @@ impl From<&commands::FormulaSpec> for FormulaSpec {
             .map(|delta| delta.into())
             .unwrap_or_default();
         if let Some(time) = spec.end_time {
-            end_delta.steps.push(DeltaStep::Time(time));
+            end_delta
+                .steps
+                .push(Spanned::new(time.span, DeltaStep::Time(time.value)));
         }
 
         Self {
@@ -49,15 +51,21 @@ impl From<&commands::WeekdaySpec> for FormulaSpec {
 
         let mut end_delta = Delta::default();
         if let Some(wd) = spec.end {
-            end_delta.steps.push(DeltaStep::Weekday(1, wd));
+            end_delta
+                .steps
+                .push(Spanned::new(wd.span, DeltaStep::Weekday(1, wd.value)));
         }
         if let Some(delta) = &spec.end_delta {
             for step in &delta.0 {
-                end_delta.steps.push((*step).into());
+                end_delta
+                    .steps
+                    .push(Spanned::new(step.span, step.value.into()));
             }
         }
         if let Some(time) = spec.end_time {
-            end_delta.steps.push(DeltaStep::Time(time));
+            end_delta
+                .steps
+                .push(Spanned::new(time.span, DeltaStep::Time(time.value)));
         }
 
         Self {
diff --git a/src/files/commands.rs b/src/files/commands.rs
index 178c106..f5be0a0 100644
--- a/src/files/commands.rs
+++ b/src/files/commands.rs
@@ -1,5 +1,48 @@
+use std::fmt;
+
 use chrono::NaiveDate;
 
+#[derive(Debug, Clone, Copy)]
+pub struct Span {
+    pub start: usize,
+    pub end: usize,
+}
+
+impl<'a> From<&pest::Span<'a>> for Span {
+    fn from(pspan: &pest::Span<'a>) -> Self {
+        Self {
+            start: pspan.start(),
+            end: pspan.end(),
+        }
+    }
+}
+
+#[derive(Clone, Copy)]
+pub struct Spanned<T> {
+    pub span: Span,
+    pub value: T,
+}
+
+impl<T: fmt::Debug> fmt::Debug for Spanned<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        self.value.fmt(f)
+    }
+}
+
+impl<T> Spanned<T> {
+    pub fn new(span: Span, value: T) -> Self {
+        Self { span, value }
+    }
+}
+
+// I don't know how one would write this. It works as a polymorphic standalone
+// function, but not in an impl block.
+// impl<S, T: Into<S>> Spanned<T> {
+//     pub fn convert(&self) -> Spanned<S> {
+//         Self::new(self.span, self.value.into())
+//     }
+// }
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub struct Time {
     pub hour: u8,
@@ -95,7 +138,7 @@ impl DeltaStep {
 }
 
 #[derive(Debug, Default)]
-pub struct Delta(pub Vec<DeltaStep>);
+pub struct Delta(pub Vec<Spanned<DeltaStep>>);
 
 #[derive(Debug)]
 pub struct Repeat {
@@ -110,9 +153,9 @@ pub struct DateSpec {
     pub start: NaiveDate,
     pub start_delta: Option<Delta>,
     pub start_time: Option<Time>,
-    pub end: Option<NaiveDate>,
+    pub end: Option<Spanned<NaiveDate>>,
     pub end_delta: Option<Delta>,
-    pub end_time: Option<Time>,
+    pub end_time: Option<Spanned<Time>>,
     pub repeat: Option<Repeat>,
 }
 
@@ -120,9 +163,9 @@ pub struct DateSpec {
 pub struct WeekdaySpec {
     pub start: Weekday,
     pub start_time: Option<Time>,
-    pub end: Option<Weekday>,
+    pub end: Option<Spanned<Weekday>>,
     pub end_delta: Option<Delta>,
-    pub end_time: Option<Time>,
+    pub end_time: Option<Spanned<Time>>,
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -289,7 +332,7 @@ pub struct FormulaSpec {
     pub start_delta: Option<Delta>,
     pub start_time: Option<Time>,
     pub end_delta: Option<Delta>,
-    pub end_time: Option<Time>,
+    pub end_time: Option<Spanned<Time>>,
 }
 
 #[derive(Debug)]
@@ -368,6 +411,7 @@ pub struct BirthdaySpec {
 pub struct Birthday {
     pub title: String,
     pub when: BirthdaySpec,
+    // pub until: Option<NaiveDate>, // TODO Add UNTIL to birthday
     pub desc: Vec<String>,
 }
 
diff --git a/src/files/format.rs b/src/files/format.rs
index e99086f..76921de 100644
--- a/src/files/format.rs
+++ b/src/files/format.rs
@@ -4,9 +4,15 @@ use chrono::Datelike;
 
 use super::commands::{
     Birthday, BirthdaySpec, Command, DateSpec, Delta, DeltaStep, Done, DoneDate, Expr, File,
-    FormulaSpec, Note, Repeat, Spec, Task, Time, Var, Weekday, WeekdaySpec,
+    FormulaSpec, Note, Repeat, Spanned, Spec, Task, Time, Var, Weekday, WeekdaySpec,
 };
 
+impl<T: fmt::Display> fmt::Display for Spanned<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.value.fmt(f)
+    }
+}
+
 fn format_desc(f: &mut fmt::Formatter<'_>, desc: &[String]) -> fmt::Result {
     for line in desc {
         if line.is_empty() {
@@ -46,7 +52,7 @@ impl fmt::Display for Delta {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let mut sign = 0;
         for step in &self.0 {
-            format_delta_step(f, step, &mut sign)?;
+            format_delta_step(f, &step.value, &mut sign)?;
         }
         Ok(())
     }
diff --git a/src/files/parse.rs b/src/files/parse.rs
index 0b404be..ead0bb5 100644
--- a/src/files/parse.rs
+++ b/src/files/parse.rs
@@ -7,7 +7,7 @@ use pest::iterators::Pair;
 use pest::prec_climber::{Assoc, Operator, PrecClimber};
 use pest::{Parser, Span};
 
-use crate::files::commands::Repeat;
+use crate::files::commands::{Repeat, Spanned};
 
 use super::commands::{
     Birthday, BirthdaySpec, Command, DateSpec, Delta, DeltaStep, Done, DoneDate, Expr, File,
@@ -56,9 +56,10 @@ fn parse_title(p: Pair<'_, Rule>) -> String {
     p.as_str().trim().to_string()
 }
 
-fn parse_datum(p: Pair<'_, Rule>) -> Result<NaiveDate> {
+fn parse_datum(p: Pair<'_, Rule>) -> Result<Spanned<NaiveDate>> {
     assert_eq!(p.as_rule(), Rule::datum);
-    let span = p.as_span();
+    let pspan = p.as_span();
+    let span = (&pspan).into();
     let mut p = p.into_inner();
 
     let year = p.next().unwrap().as_str().parse().unwrap();
@@ -68,14 +69,15 @@ fn parse_datum(p: Pair<'_, Rule>) -> Result<NaiveDate> {
     assert_eq!(p.next(), None);
 
     match NaiveDate::from_ymd_opt(year, month, day) {
-        Some(date) => Ok(date),
-        None => fail(span, "invalid date"),
+        Some(date) => Ok(Spanned::new(span, date)),
+        None => fail(pspan, "invalid date"),
     }
 }
 
-fn parse_time(p: Pair<'_, Rule>) -> Result<Time> {
+fn parse_time(p: Pair<'_, Rule>) -> Result<Spanned<Time>> {
     assert_eq!(p.as_rule(), Rule::time);
-    let span = p.as_span();
+    let pspan = p.as_span();
+    let span = (&pspan).into();
     let mut p = p.into_inner();
 
     let hour = p.next().unwrap().as_str().parse().unwrap();
@@ -84,8 +86,8 @@ fn parse_time(p: Pair<'_, Rule>) -> Result<Time> {
     assert_eq!(p.next(), None);
 
     match Time::new(hour, min) {
-        Some(time) => Ok(time),
-        None => fail(span, "invalid time"),
+        Some(time) => Ok(Spanned::new(span, time)),
+        None => fail(pspan, "invalid time"),
     }
 }
 
@@ -138,9 +140,10 @@ fn parse_amount(p: Pair<'_, Rule>) -> Amount {
     Amount { sign, value }
 }
 
-fn parse_weekday(p: Pair<'_, Rule>) -> Weekday {
+fn parse_weekday(p: Pair<'_, Rule>) -> Spanned<Weekday> {
     assert_eq!(p.as_rule(), Rule::weekday);
-    match p.as_str() {
+    let span = (&p.as_span()).into();
+    let wd = match p.as_str() {
         "mon" => Weekday::Monday,
         "tue" => Weekday::Tuesday,
         "wed" => Weekday::Wednesday,
@@ -149,32 +152,34 @@ fn parse_weekday(p: Pair<'_, Rule>) -> Weekday {
         "sat" => Weekday::Saturday,
         "sun" => Weekday::Sunday,
         _ => unreachable!(),
-    }
+    };
+    Spanned::new(span, wd)
 }
 
-fn parse_delta_weekdays(p: Pair<'_, Rule>, sign: &mut Option<Sign>) -> Result<DeltaStep> {
+fn parse_delta_weekdays(p: Pair<'_, Rule>, sign: &mut Option<Sign>) -> Result<Spanned<DeltaStep>> {
     assert_eq!(p.as_rule(), Rule::delta_weekdays);
-    let span = p.as_span();
+    let pspan = p.as_span();
+    let span = (&pspan).into();
     let mut p = p.into_inner();
 
     let amount = parse_amount(p.next().unwrap()).with_prev_sign(*sign);
-    let weekday = parse_weekday(p.next().unwrap());
+    let weekday = parse_weekday(p.next().unwrap()).value;
 
     assert_eq!(p.next(), None);
 
     let value = amount
         .value()
-        .ok_or_else(|| error(span, "ambiguous sign"))?;
+        .ok_or_else(|| error(pspan, "ambiguous sign"))?;
     *sign = amount.sign;
 
-    Ok(DeltaStep::Weekday(value, weekday))
+    Ok(Spanned::new(span, DeltaStep::Weekday(value, weekday)))
 }
 
 fn parse_delta_step(
     p: Pair<'_, Rule>,
     sign: &mut Option<Sign>,
     f: impl FnOnce(i32) -> DeltaStep,
-) -> Result<DeltaStep> {
+) -> Result<Spanned<DeltaStep>> {
     assert!(matches!(
         p.as_rule(),
         Rule::delta_years
@@ -186,14 +191,15 @@ fn parse_delta_step(
             | Rule::delta_minutes
     ));
 
-    let span = p.as_span();
+    let pspan = p.as_span();
+    let span = (&pspan).into();
     let amount = parse_amount(p.into_inner().next().unwrap()).with_prev_sign(*sign);
     let value = amount
         .value()
-        .ok_or_else(|| error(span, "ambiguous sign"))?;
+        .ok_or_else(|| error(pspan, "ambiguous sign"))?;
 
     *sign = amount.sign;
-    Ok(f(value))
+    Ok(Spanned::new(span, f(value)))
 }
 
 fn parse_delta(p: Pair<'_, Rule>) -> Result<Delta> {
@@ -226,9 +232,9 @@ fn parse_date_fixed_start(p: Pair<'_, Rule>, spec: &mut DateSpec) -> Result<()>
 
     for p in p.into_inner() {
         match p.as_rule() {
-            Rule::datum => spec.start = parse_datum(p)?,
+            Rule::datum => spec.start = parse_datum(p)?.value,
             Rule::delta => spec.start_delta = Some(parse_delta(p)?),
-            Rule::time => spec.start_time = Some(parse_time(p)?),
+            Rule::time => spec.start_time = Some(parse_time(p)?.value),
             _ => unreachable!(),
         }
     }
@@ -431,7 +437,7 @@ fn parse_date_expr_start(p: Pair<'_, Rule>, spec: &mut FormulaSpec) -> Result<()
         match p.as_rule() {
             Rule::paren_expr => spec.start = Some(parse_expr(p.into_inner().next().unwrap())),
             Rule::delta => spec.start_delta = Some(parse_delta(p)?),
-            Rule::time => spec.start_time = Some(parse_time(p)?),
+            Rule::time => spec.start_time = Some(parse_time(p)?.value),
             _ => unreachable!(),
         }
     }
@@ -480,8 +486,8 @@ fn parse_date_weekday_start(p: Pair<'_, Rule>, spec: &mut WeekdaySpec) -> Result
 
     for p in p.into_inner() {
         match p.as_rule() {
-            Rule::weekday => spec.start = parse_weekday(p),
-            Rule::time => spec.start_time = Some(parse_time(p)?),
+            Rule::weekday => spec.start = parse_weekday(p).value,
+            Rule::time => spec.start_time = Some(parse_time(p)?.value),
             _ => unreachable!(),
         }
     }
@@ -539,17 +545,20 @@ fn parse_date(p: Pair<'_, Rule>) -> Result<Spec> {
 
 fn parse_from(p: Pair<'_, Rule>) -> Result<NaiveDate> {
     assert_eq!(p.as_rule(), Rule::from);
-    parse_datum(p.into_inner().next().unwrap())
+    let datum = parse_datum(p.into_inner().next().unwrap())?;
+    Ok(datum.value)
 }
 
 fn parse_until(p: Pair<'_, Rule>) -> Result<NaiveDate> {
     assert_eq!(p.as_rule(), Rule::until);
-    parse_datum(p.into_inner().next().unwrap())
+    let datum = parse_datum(p.into_inner().next().unwrap())?;
+    Ok(datum.value)
 }
 
 fn parse_except(p: Pair<'_, Rule>) -> Result<NaiveDate> {
     assert_eq!(p.as_rule(), Rule::except);
-    parse_datum(p.into_inner().next().unwrap())
+    let datum = parse_datum(p.into_inner().next().unwrap())?;
+    Ok(datum.value)
 }
 
 fn parse_donedate(p: Pair<'_, Rule>) -> Result<DoneDate> {
@@ -561,24 +570,24 @@ fn parse_donedate(p: Pair<'_, Rule>) -> Result<DoneDate> {
     // the list ;-;
     Ok(match ps.len() {
         1 => DoneDate::Date {
-            root: parse_datum(ps.pop().unwrap())?,
+            root: parse_datum(ps.pop().unwrap())?.value,
         },
         2 => match ps[1].as_rule() {
             Rule::time => DoneDate::DateWithTime {
-                root_time: parse_time(ps.pop().unwrap())?,
-                root: parse_datum(ps.pop().unwrap())?,
+                root_time: parse_time(ps.pop().unwrap())?.value,
+                root: parse_datum(ps.pop().unwrap())?.value,
             },
             Rule::datum => DoneDate::DateToDate {
-                other: parse_datum(ps.pop().unwrap())?,
-                root: parse_datum(ps.pop().unwrap())?,
+                other: parse_datum(ps.pop().unwrap())?.value,
+                root: parse_datum(ps.pop().unwrap())?.value,
             },
             _ => unreachable!(),
         },
         4 => DoneDate::DateToDateWithTime {
-            other_time: parse_time(ps.pop().unwrap())?,
-            other: parse_datum(ps.pop().unwrap())?,
-            root_time: parse_time(ps.pop().unwrap())?,
-            root: parse_datum(ps.pop().unwrap())?,
+            other_time: parse_time(ps.pop().unwrap())?.value,
+            other: parse_datum(ps.pop().unwrap())?.value,
+            root_time: parse_time(ps.pop().unwrap())?.value,
+            root: parse_datum(ps.pop().unwrap())?.value,
         },
         _ => unreachable!(),
     })
@@ -588,7 +597,7 @@ fn parse_done(p: Pair<'_, Rule>) -> Result<Done> {
     assert_eq!(p.as_rule(), Rule::done);
     let mut p = p.into_inner();
 
-    let done_at = parse_datum(p.next().unwrap())?;
+    let done_at = parse_datum(p.next().unwrap())?.value;
     let date = if let Some(p) = p.next() {
         Some(parse_donedate(p)?)
     } else {