cli: Add support for .headers command

The `.headers` command takes `on` and `off` as parameter, supported by
SQLite, which controls whether result set header is printed in list mode.

cli/app.rs

@@ -1,6 +1,6 @@
 use crate::{
     commands::{
-        args::{EchoMode, TimerMode},
+        args::{EchoMode, HeadersMode, TimerMode},
         import::ImportFile,
         Command, CommandParser,
     },
@@ -676,6 +676,12 @@ impl Limbo {
                         TimerMode::Off => false,
                     };
                 }
+                Command::Headers(headers_mode) => {
+                    self.opts.headers = match headers_mode.mode {
+                        HeadersMode::On => true,
+                        HeadersMode::Off => false,
+                    };
+                }
             },
         }
     }
@@ -688,7 +694,9 @@ impl Limbo {
     ) -> anyhow::Result<()> {
         match output {
             Ok(Some(ref mut rows)) => match self.opts.output_mode {
-                OutputMode::List => loop {
+                OutputMode::List => {
+                    let mut headers_printed = false;
+                    loop {
                         if self.interrupt_count.load(Ordering::SeqCst) > 0 {
                             println!("Query interrupted.");
                             return Ok(());
@@ -701,15 +709,31 @@ impl Limbo {
                                 if let Some(ref mut stats) = statistics {
                                     stats.execute_time_elapsed_samples.push(start.elapsed());
                                 }
+
+                                // Print headers if enabled and not already printed
+                                if self.opts.headers && !headers_printed {
+                                    for i in 0..rows.num_columns() {
+                                        if i > 0 {
+                                            let _ = self.writer.write(b"|");
+                                        }
+                                        let _ =
+                                            self.writer.write(rows.get_column_name(i).as_bytes());
+                                    }
+                                    let _ = self.writeln("");
+                                    headers_printed = true;
+                                }
+
                                 let row = rows.row().unwrap();
                                 for (i, value) in row.get_values().enumerate() {
                                     if i > 0 {
                                         let _ = self.writer.write(b"|");
                                     }
                                     if matches!(value, Value::Null) {
-                                    let _ = self.writer.write(self.opts.null_value.as_bytes())?;
+                                        let _ =
+                                            self.writer.write(self.opts.null_value.as_bytes())?;
                                     } else {
-                                    let _ = self.writer.write(format!("{}", value).as_bytes())?;
+                                        let _ =
+                                            self.writer.write(format!("{}", value).as_bytes())?;
                                     }
                                 }
                                 let _ = self.writeln("");
@@ -739,11 +763,14 @@ impl Limbo {
                                 if let Some(ref mut stats) = statistics {
                                     stats.execute_time_elapsed_samples.push(start.elapsed());
                                 }
-                            let _ = self.writeln(err.to_string());
+                                let report =
+                                    miette::Error::from(err).with_source_code(sql.to_owned());
+                                let _ = self.write_fmt(format_args!("{:?}", report));
                                 break;
                             }
                         }
-                },
+                    }
+                }
                 OutputMode::Pretty => {
                     if self.interrupt_count.load(Ordering::SeqCst) > 0 {
                         println!("Query interrupted.");

cli/commands/args.rs

@@ -124,3 +124,14 @@ pub struct TimerArgs {
     #[arg(value_enum)]
     pub mode: TimerMode,
 }
+
+#[derive(Debug, Clone, Args)]
+pub struct HeadersArgs {
+    pub mode: HeadersMode,
+}
+
+#[derive(ValueEnum, Copy, Clone, Debug, PartialEq, Eq)]
+pub enum HeadersMode {
+    On,
+    Off,
+}

cli/commands/mod.rs

@@ -2,8 +2,8 @@ pub mod args;
 pub mod import;
 
 use args::{
-    CwdArgs, EchoArgs, ExitArgs, IndexesArgs, LoadExtensionArgs, NullValueArgs, OpcodesArgs,
-    OpenArgs, OutputModeArgs, SchemaArgs, SetOutputArgs, TablesArgs, TimerArgs,
+    CwdArgs, EchoArgs, ExitArgs, HeadersArgs, IndexesArgs, LoadExtensionArgs, NullValueArgs,
+    OpcodesArgs, OpenArgs, OutputModeArgs, SchemaArgs, SetOutputArgs, TablesArgs, TimerArgs,
 };
 use clap::Parser;
 use import::ImportArgs;
@@ -77,6 +77,9 @@ pub enum Command {
     ListIndexes(IndexesArgs),
     #[command(name = "timer", display_name = ".timer")]
     Timer(TimerArgs),
+    /// Toggle column headers on/off in list mode
+    #[command(name = "headers", display_name = ".headers")]
+    Headers(HeadersArgs),
 }
 
 const _HELP_TEMPLATE: &str = "{before-help}{name}

cli/input.rs

@@ -83,6 +83,7 @@ pub struct Settings {
     pub io: Io,
     pub tracing_output: Option<String>,
     pub timer: bool,
+    pub headers: bool,
 }
 
 impl From<Opts> for Settings {
@@ -107,6 +108,7 @@ impl From<Opts> for Settings {
             },
             tracing_output: opts.tracing_output,
             timer: false,
+            headers: false,
         }
     }
 }
@@ -115,7 +117,7 @@ impl std::fmt::Display for Settings {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(
             f,
-            "Settings:\nOutput mode: {}\nDB: {}\nOutput: {}\nNull value: {}\nCWD: {}\nEcho: {}",
+            "Settings:\nOutput mode: {}\nDB: {}\nOutput: {}\nNull value: {}\nCWD: {}\nEcho: {}\nHeaders: {}",
             self.output_mode,
             self.db_file,
             match self.is_stdout {
@@ -127,6 +129,10 @@ impl std::fmt::Display for Settings {
             match self.echo {
                 true => "on",
                 false => "off",
+            },
+            match self.headers {
+                true => "on",
+                false => "off",
             }
         )
     }
@@ -221,6 +227,12 @@ pub const AFTER_HELP_MSG: &str = r#"Usage Examples:
 14. To show names of indexes:
    .indexes ?TABLE?
 
+15. To turn on column headers in list mode:
+   .headers on
+
+16. To turn off column headers in list mode:
+   .headers off
+
 Note:
 - All SQL commands must end with a semicolon (;).
 - Special commands start with a dot (.) and are not required to end with a semicolon."#;