Add WriteError type, convert print_lines to return a result

src/error.rs

@@ -7,6 +7,18 @@ pub enum TealdeerError {
     CacheError(String),
     ConfigError(String),
     UpdateError(String),
+    WriteError(String),
+}
+
+impl TealdeerError {
+    pub(crate) fn message(&self) -> &str {
+        match self {
+            Self::CacheError(msg)
+            | Self::ConfigError(msg)
+            | Self::UpdateError(msg)
+            | Self::WriteError(msg) => msg,
+        }
+    }
 }
 
 impl From<ReqwestError> for TealdeerError {
@@ -21,6 +33,7 @@ impl fmt::Display for TealdeerError {
             Self::CacheError(e) => write!(f, "CacheError: {}", e),
             Self::ConfigError(e) => write!(f, "ConfigError: {}", e),
             Self::UpdateError(e) => write!(f, "UpdateError: {}", e),
+            Self::WriteError(e) => write!(f, "WriteError: {}", e),
         }
     }
 }

src/formatter.rs

@@ -6,6 +6,7 @@ use ansi_term::{ANSIString, ANSIStrings};
 use log::debug;
 
 use crate::config::Config;
+use crate::error::TealdeerError::{self, WriteError};
 use crate::tokenizer::Tokenizer;
 use crate::types::LineType;
 
@@ -63,17 +64,21 @@ fn format_code(command: &str, text: &str, config: &Config) -> String {
 }
 
 /// Print a token stream to an ANSI terminal.
-pub fn print_lines<R, T>(writer: &mut T, tokenizer: &mut Tokenizer<R>, config: &Config)
+pub fn print_lines<T, R>(
+    writer: &mut T,
+    tokenizer: &mut Tokenizer<R>,
+    config: &Config,
+) -> Result<(), TealdeerError>
 where
-    R: BufRead,
     T: Write,
+    R: BufRead,
 {
     let mut command = String::new();
     while let Some(token) = tokenizer.next_token() {
         match token {
             LineType::Empty => {
                 if !config.display.compact {
-                    writeln!(writer).unwrap();
+                    writeln!(writer).map_err(|e| WriteError(e.to_string()))?;
                 }
             }
             LineType::Title(title) => {
@@ -85,16 +90,19 @@ where
                 debug!("Detected command name: {}", &command);
             }
             LineType::Description(text) => {
-                writeln!(writer, "  {}", config.style.description.paint(text)).unwrap();
+                writeln!(writer, "  {}", config.style.description.paint(text))
+                    .map_err(|e| WriteError(e.to_string()))?;
             }
             LineType::ExampleText(text) => {
-                writeln!(writer, "  {}", config.style.example_text.paint(text)).unwrap();
+                writeln!(writer, "  {}", config.style.example_text.paint(text))
+                    .map_err(|e| WriteError(e.to_string()))?;
             }
             LineType::ExampleCode(text) => {
-                writeln!(writer, "      {}", &format_code(&command, &text, &config)).unwrap();
+                writeln!(writer, "      {}", &format_code(&command, &text, &config))
+                    .map_err(|e| WriteError(e.to_string()))?;
             }
             LineType::Other(text) => debug!("Unknown line type: {:?}", text),
         }
     }
-    writeln!(writer).unwrap();
+    writeln!(writer).map_err(|e| WriteError(e.to_string()))
 }

src/main.rs

@@ -41,7 +41,7 @@ mod types;
 use crate::cache::{Cache, PageLookupResult};
 use crate::config::{get_config_dir, get_config_path, make_default_config, Config, MAX_CACHE_AGE};
 use crate::dedup::Dedup;
-use crate::error::TealdeerError::{CacheError, ConfigError, UpdateError};
+use crate::error::TealdeerError::ConfigError;
 use crate::formatter::print_lines;
 use crate::tokenizer::Tokenizer;
 use crate::types::{ColorOptions, OsType};
@@ -84,7 +84,6 @@ fn print_page(
     enable_markdown: bool,
     config: &Config,
 ) -> Result<(), String> {
-    // Open file
     for path in page.paths() {
         let file = File::open(path).map_err(|msg| format!("Could not open file: {}", msg))?;
         let reader = BufReader::new(file);
@@ -101,7 +100,7 @@ fn print_page(
             // Create tokenizer and print output
             let mut tokenizer = Tokenizer::new(reader);
             print_lines(&mut handle, &mut tokenizer, &config)
-                .map_err(|_| "Could not write to stdout".to_string())?;
+                .map_err(|e| format!("Could not write to stdout: {}", e.message()))?;
         };
 
         handle
@@ -164,11 +163,7 @@ fn check_cache(args: &Args, enable_styles: bool) {
 /// Clear the cache
 fn clear_cache(quietly: bool) {
     Cache::clear().unwrap_or_else(|e| {
-        match e {
-            CacheError(msg) | ConfigError(msg) | UpdateError(msg) => {
-                eprintln!("Could not delete cache: {}", msg)
-            }
-        };
+        eprintln!("Could not delete cache: {}", e.message());
         process::exit(1);
     });
     if !quietly {
@@ -179,11 +174,7 @@ fn clear_cache(quietly: bool) {
 /// Update the cache
 fn update_cache(cache: &Cache, quietly: bool) {
     cache.update().unwrap_or_else(|e| {
-        match e {
-            CacheError(msg) | ConfigError(msg) | UpdateError(msg) => {
-                eprintln!("Could not update cache: {}", msg)
-            }
-        };
+        eprintln!("Could not update cache: {}", e.message());
         process::exit(1);
     });
     if !quietly {
@@ -461,11 +452,7 @@ fn main() {
 
         // Get list of pages
         let pages = cache.list_pages().unwrap_or_else(|e| {
-            match e {
-                CacheError(msg) | ConfigError(msg) | UpdateError(msg) => {
-                    eprintln!("Could not get list of pages: {}", msg)
-                }
-            }
+            eprintln!("Could not get list of pages: {}", e.message());
             process::exit(1);
         });