chore(code): move crates/sprout to crates/boot and name it edera-sprout-boot

crates/boot/src/options/parser.rs

@@ -0,0 +1,153 @@
+use crate::options::env;
+use alloc::collections::BTreeMap;
+use alloc::string::{String, ToString};
+use anyhow::{Context, Result, bail};
+use core::ptr::null_mut;
+use log::info;
+use uefi_raw::Status;
+
+/// The type of option. This disambiguates different behavior
+/// of how options are handled.
+#[derive(Debug, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub enum OptionForm {
+    /// A flag, like --verbose.
+    Flag,
+    /// A value, in the form --abc 123 or --abc=123.
+    Value,
+    /// Help flag, like --help.
+    Help,
+}
+
+/// The description of an option, used in the options parser
+/// to make decisions about how to progress.
+#[derive(Debug, Clone)]
+pub struct OptionDescription<'a> {
+    /// The description of the option.
+    pub description: &'a str,
+    /// The type of option to parse as.
+    pub form: OptionForm,
+}
+
+/// Represents a type that can be parsed from command line arguments.
+/// This is a super minimal options parser mechanism just for Sprout.
+pub trait OptionsRepresentable {
+    /// The output type that parsing will produce.
+    type Output;
+
+    /// The configured options for this type. This should describe all the options
+    /// that are valid to produce the type. The left hand side is the name of the option,
+    /// and the right hand side is the description.
+    fn options() -> &'static [(&'static str, OptionDescription<'static>)];
+
+    /// Produces the type by taking the `options` and processing it into the output.
+    fn produce(options: BTreeMap<String, Option<String>>) -> Result<Self::Output>;
+
+    /// For minimalism, we don't want a full argument parser. Instead, we use
+    /// a simple --xyz = xyz: None and --abc 123 = abc: Some("123") format.
+    /// We also support --abc=123 = abc: Some("123") format.
+    fn parse_raw() -> Result<BTreeMap<String, Option<String>>> {
+        // Access the configured options for this type.
+        let configured: BTreeMap<_, _> = BTreeMap::from_iter(Self::options().to_vec());
+
+        // Collect all the arguments to Sprout.
+        // Skip the first argument, which is the path to our executable.
+        let args = env::args()?;
+
+        // Represent options as key-value pairs.
+        let mut options = BTreeMap::new();
+
+        // Iterators makes this way easier.
+        let mut iterator = args.into_iter().peekable();
+
+        loop {
+            // Consume the next option, if any.
+            let Some(option) = iterator.next() else {
+                break;
+            };
+
+            // If the option doesn't start with --, that is invalid.
+            if !option.starts_with("--") {
+                bail!("invalid option: {option}");
+            }
+
+            // Strip the -- prefix off.
+            let mut option = option["--".len()..].trim().to_string();
+
+            // An optional value.
+            let mut value = None;
+
+            // Check if the option is of the form --abc=123
+            if let Some((part_key, part_value)) = option.split_once('=') {
+                let part_key = part_key.to_string();
+                let part_value = part_value.to_string();
+                option = part_key;
+                value = Some(part_value);
+            }
+
+            // Error on empty option names.
+            if option.is_empty() {
+                bail!("invalid empty option");
+            }
+
+            // Find the description of the configured option, if any.
+            let Some(description) = configured.get(option.as_str()) else {
+                bail!("invalid option: --{option}");
+            };
+
+            // Check if the option requires a value and error if none was provided.
+            if description.form == OptionForm::Value && value.is_none() {
+                // Check for the next value.
+                let maybe_next = iterator.peek();
+
+                // If the next value isn't another option, set the value to the next value.
+                // Otherwise, it is None.
+                value = if let Some(next) = maybe_next
+                    && !next.starts_with("--")
+                {
+                    iterator.next()
+                } else {
+                    None
+                };
+            }
+
+            // If the option form does not support a value and there is a value, error.
+            if description.form != OptionForm::Value && value.is_some() {
+                bail!("option --{} does not take a value", option);
+            }
+
+            // Handle the --help flag case.
+            if description.form == OptionForm::Help {
+                // Generic configured options output.
+                info!("Configured Options:");
+                for (name, description) in &configured {
+                    info!(
+                        "  --{}{}: {}",
+                        name,
+                        if description.form == OptionForm::Value {
+                            " <value>"
+                        } else {
+                            ""
+                        },
+                        description.description
+                    );
+                }
+                // Exit because the help has been displayed.
+                unsafe {
+                    uefi::boot::exit(uefi::boot::image_handle(), Status::SUCCESS, 0, null_mut());
+                };
+            }
+
+            // Insert the option and the value into the map.
+            options.insert(option, value);
+        }
+        Ok(options)
+    }
+
+    /// Parses the program arguments as a [Self::Output], calling [Self::parse_raw] and [Self::produce].
+    fn parse() -> Result<Self::Output> {
+        // Parse the program arguments into a raw map.
+        let options = Self::parse_raw().context("unable to parse options")?;
+        // Produce the options from the map.
+        Self::produce(options)
+    }
+}