simple web server

src/extract.rs

@@ -1,6 +1,4 @@
-use std::collections::HashMap;
-use std::fmt::Write;
-use std::rc::Rc;
+use std::{collections::HashMap, fmt::Write, sync::Arc};
 
 use lazy_static::lazy_static;
 use pdf::{backend::Backend, content::Operation, primitive::Primitive};
@@ -21,15 +19,21 @@ const DATE_DISPLAY_FORMAT: &[time::format_description::FormatItem] =
     time::macros::format_description!("[year]-[month]-[day]");
 
 pub struct DataSet {
-    pub columns: Vec<Rc<String>>,
+    pub columns: Vec<Arc<String>>,
     pub rows: Vec<DataPoint>,
 }
 
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error("PDF contained no data rows")]
+    NoData,
+}
+
 impl DataSet {
-    pub fn extract<B: Backend>(doc: &pdf::file::File<B>) -> Option<Self> {
+    pub fn extract<B: Backend>(doc: &pdf::file::File<B>) -> Result<Self, Error> {
         let mut doc_iter = DocumentIterator::new(doc).peekable();
 
-        let mut columns: Vec<(Rc<String>, f32)> = Vec::new();
+        let mut columns: Vec<(Arc<String>, f32)> = Vec::new();
         let mut rows: Vec<DataPoint> = Vec::new();
 
         let (mut current_datapoint, mut current_y) = loop {
@@ -39,7 +43,7 @@ impl DataSet {
                     let column_x = text.x;
                     while let Some(more) = doc_iter.peek() {
                         if is_new_column_header(&more.text) || DATE_REGEX.is_match(&more.text) {
-                            columns.push((Rc::new(column_name), column_x));
+                            columns.push((Arc::new(column_name), column_x));
                             break;
                         }
                         column_name += " ";
@@ -53,7 +57,7 @@ impl DataSet {
                     );
                 }
             } else {
-                return None;
+                return Err(Error::NoData);
             }
         };
 
@@ -79,40 +83,44 @@ impl DataSet {
             }
         }
 
-        Some(Self {
+        Ok(Self {
             columns: columns.into_iter().map(|(column, _)| column).collect(),
             rows,
         })
     }
 
+    pub fn csv_header(&self) -> Result<String, std::fmt::Error> {
+        let mut header = String::from("Date");
+        for column in self.columns.iter() {
+            write!(&mut header, ",{}", column)?;
+        }
+        Ok(header)
+    }
+
+    pub fn csv_row(&self, datapoint: &DataPoint) -> Result<String, std::fmt::Error> {
+        let mut csv_row = datapoint
+            .date
+            .format(DATE_DISPLAY_FORMAT)
+            .expect("Failed to format date!");
+        for column in self.columns.iter() {
+            if let Some(val) = datapoint.values.get(column) {
+                write!(&mut csv_row, ",{}", val)?;
+            } else {
+                write!(&mut csv_row, ",")?;
+            }
+        }
+        Ok(csv_row)
+    }
+
     pub fn csv_rows(&self) -> impl Iterator<Item = Result<String, std::fmt::Error>> + '_ {
-        std::iter::once_with(|| {
-            let mut header = String::from("Date");
-            for column in self.columns.iter() {
-                write!(&mut header, ",{}", column)?;
-            }
-            Ok(header)
-        })
-        .chain(self.rows.iter().map(|datapoint| {
-            let mut csv_row = datapoint
-                .date
-                .format(DATE_DISPLAY_FORMAT)
-                .expect("Failed to format date!");
-            for column in self.columns.iter() {
-                if let Some(val) = datapoint.values.get(column) {
-                    write!(&mut csv_row, ",{}", val)?;
-                } else {
-                    write!(&mut csv_row, ",")?;
-                }
-            }
-            Ok(csv_row)
-        }))
+        std::iter::once_with(|| self.csv_header())
+            .chain(self.rows.iter().map(|datapoint| self.csv_row(datapoint)))
     }
 }
 
 pub struct DataPoint {
     pub date: Date,
-    pub values: HashMap<Rc<String>, u32>,
+    pub values: HashMap<Arc<String>, u32>,
 }
 
 impl DataPoint {