change a BTreeMap to a HashMap

azalea-brigadier/src/command_dispatcher.rs

@@ -0,0 +1,711 @@
+use crate::{
+    builder::argument_builder::ArgumentBuilder,
+    context::{CommandContext, CommandContextBuilder},
+    exceptions::{BuiltInExceptions, CommandSyntaxException},
+    parse_results::ParseResults,
+    string_reader::StringReader,
+    tree::CommandNode,
+};
+use std::{cell::RefCell, cmp::Ordering, collections::HashMap, marker::PhantomData, mem, rc::Rc};
+
+#[derive(Default)]
+pub struct CommandDispatcher<S> {
+    root: Rc<RefCell<CommandNode<S>>>,
+    _marker: PhantomData<S>,
+}
+
+impl<S> CommandDispatcher<S> {
+    pub fn new() -> Self {
+        Self {
+            root: Rc::new(RefCell::new(CommandNode::default())),
+            _marker: PhantomData,
+        }
+    }
+
+    pub fn register(&mut self, node: ArgumentBuilder<S>) -> Rc<RefCell<CommandNode<S>>> {
+        let build = Rc::new(RefCell::new(node.build()));
+        self.root.borrow_mut().add_child(&build);
+        build
+    }
+
+    pub fn parse(&self, command: StringReader, source: Rc<S>) -> ParseResults<S> {
+        let context = CommandContextBuilder::new(
+            Rc::new(self.clone()),
+            source,
+            self.root.clone(),
+            command.cursor(),
+        );
+        self.parse_nodes(&self.root, &command, context).unwrap()
+    }
+
+    fn parse_nodes(
+        &self,
+        node: &Rc<RefCell<CommandNode<S>>>,
+        original_reader: &StringReader,
+        context_so_far: CommandContextBuilder<S>,
+    ) -> Result<ParseResults<S>, CommandSyntaxException> {
+        let source = context_so_far.source.clone();
+        let mut errors = HashMap::<Rc<CommandNode<S>>, CommandSyntaxException>::new();
+        let mut potentials: Vec<ParseResults<S>> = vec![];
+        let cursor = original_reader.cursor();
+
+        for child in node
+            .borrow()
+            .get_relevant_nodes(&mut original_reader.clone())
+        {
+            if !child.borrow().can_use(source.clone()) {
+                continue;
+            }
+            let mut context = context_so_far.clone();
+            let mut reader = original_reader.clone();
+
+            let parse_with_context_result =
+                child.borrow().parse_with_context(&mut reader, &mut context);
+            if let Err(ex) = parse_with_context_result {
+                errors.insert(
+                    Rc::new((*child.borrow()).clone()),
+                    BuiltInExceptions::DispatcherParseException {
+                        message: ex.message(),
+                    }
+                    .create_with_context(&reader),
+                );
+                reader.cursor = cursor;
+                continue;
+            }
+            if reader.can_read() && reader.peek() != ' ' {
+                errors.insert(
+                    Rc::new((*child.borrow()).clone()),
+                    BuiltInExceptions::DispatcherExpectedArgumentSeparator
+                        .create_with_context(&reader),
+                );
+                reader.cursor = cursor;
+                continue;
+            }
+
+            context.with_command(&child.borrow().command);
+            if reader.can_read_length(if child.borrow().redirect.is_none() {
+                2
+            } else {
+                1
+            }) {
+                reader.skip();
+                if let Some(redirect) = &child.borrow().redirect {
+                    let child_context = CommandContextBuilder::new(
+                        Rc::new(self.clone()),
+                        source,
+                        redirect.clone(),
+                        reader.cursor,
+                    );
+                    let parse = self
+                        .parse_nodes(redirect, &reader, child_context)
+                        .expect("Parsing nodes failed");
+                    context.with_child(Rc::new(parse.context));
+                    return Ok(ParseResults {
+                        context,
+                        reader: parse.reader,
+                        exceptions: parse.exceptions,
+                    });
+                } else {
+                    let parse = self
+                        .parse_nodes(&child, &reader, context)
+                        .expect("Parsing nodes failed");
+                    potentials.push(parse);
+                }
+            } else {
+                potentials.push(ParseResults {
+                    context,
+                    reader,
+                    exceptions: HashMap::new(),
+                });
+            }
+        }
+
+        if !potentials.is_empty() {
+            if potentials.len() > 1 {
+                potentials.sort_by(|a, b| {
+                    if !a.reader.can_read() && b.reader.can_read() {
+                        return Ordering::Less;
+                    };
+                    if a.reader.can_read() && !b.reader.can_read() {
+                        return Ordering::Greater;
+                    };
+                    if a.exceptions.is_empty() && !b.exceptions.is_empty() {
+                        return Ordering::Less;
+                    };
+                    if !a.exceptions.is_empty() && b.exceptions.is_empty() {
+                        return Ordering::Greater;
+                    };
+                    Ordering::Equal
+                })
+            }
+            let best_potential = potentials.into_iter().next().unwrap();
+            return Ok(best_potential);
+        }
+
+        Ok(ParseResults {
+            context: context_so_far,
+            reader: original_reader.clone(),
+            exceptions: errors,
+        })
+    }
+
+    pub fn execute(
+        &self,
+        input: StringReader,
+        source: Rc<S>,
+    ) -> Result<i32, CommandSyntaxException> {
+        let parse = self.parse(input, source);
+        Self::execute_parsed(parse)
+    }
+
+    pub fn add_paths(
+        &self,
+        node: Rc<RefCell<CommandNode<S>>>,
+        result: &mut Vec<Vec<Rc<RefCell<CommandNode<S>>>>>,
+        parents: Vec<Rc<RefCell<CommandNode<S>>>>,
+    ) {
+        let mut current = parents;
+        current.push(node.clone());
+        result.push(current.clone());
+
+        for child in node.borrow().children.values() {
+            self.add_paths(child.clone(), result, current.clone());
+        }
+    }
+
+    pub fn get_path(&self, target: CommandNode<S>) -> Vec<String> {
+        let rc_target = Rc::new(RefCell::new(target));
+        let mut nodes: Vec<Vec<Rc<RefCell<CommandNode<S>>>>> = Vec::new();
+        self.add_paths(self.root.clone(), &mut nodes, vec![]);
+
+        for list in nodes {
+            if *list.last().expect("Nothing in list").borrow() == *rc_target.borrow() {
+                let mut result: Vec<String> = Vec::with_capacity(list.len());
+                for node in list {
+                    if node != self.root {
+                        result.push(node.borrow().name().to_string());
+                    }
+                }
+                return result;
+            }
+        }
+        vec![]
+    }
+
+    pub fn find_node(&self, path: &[&str]) -> Option<Rc<RefCell<CommandNode<S>>>> {
+        let mut node = self.root.clone();
+        for name in path {
+            if let Some(child) = node.clone().borrow().child(name) {
+                node = child
+            } else {
+                return None;
+            }
+        }
+        Some(node)
+    }
+
+    /// Executes a given pre-parsed command.
+    pub fn execute_parsed(parse: ParseResults<S>) -> Result<i32, CommandSyntaxException> {
+        if parse.reader.can_read() {
+            if parse.exceptions.len() == 1 {
+                return Err(parse.exceptions.values().next().unwrap().clone());
+            }
+            if parse.context.range.is_empty() {
+                return Err(
+                    BuiltInExceptions::DispatcherUnknownCommand.create_with_context(&parse.reader)
+                );
+            }
+            return Err(
+                BuiltInExceptions::DispatcherUnknownArgument.create_with_context(&parse.reader)
+            );
+        }
+        let mut result = 0i32;
+        let mut successful_forks = 0;
+        let mut forked = false;
+        let mut found_command = false;
+        let command = parse.reader.string();
+        let original = parse.context.build(command);
+        let mut contexts = vec![original];
+        let mut next: Vec<CommandContext<S>> = vec![];
+
+        while !contexts.is_empty() {
+            for context in contexts.iter() {
+                let child = &context.child;
+                if let Some(child) = child {
+                    println!("aaaaaaa {:?}", child);
+                    forked |= child.forks;
+                    if child.has_nodes() {
+                        found_command = true;
+                        let modifier = &context.modifier;
+                        if let Some(modifier) = modifier {
+                            let results = modifier(context);
+                            if let Ok(results) = results {
+                                if !results.is_empty() {
+                                    next.extend(results.iter().map(|s| child.copy_for(s.clone())));
+                                }
+                            } else {
+                                // TODO
+                                // self.consumer.on_command_complete(context, false, 0);
+                                if !forked {
+                                    return Err(results.err().unwrap());
+                                }
+                            }
+                        } else {
+                            next.push(child.copy_for(context.source.clone()));
+                        }
+                    }
+                } else if let Some(context_command) = &context.command {
+                    found_command = true;
+
+                    let value = context_command(context);
+                    result += value;
+                    // consumer.on_command_complete(context, true, value);
+                    successful_forks += 1;
+
+                    // TODO: allow context_command to error and handle those errors
+                }
+            }
+
+            // move next into contexts and clear next
+            mem::swap(&mut contexts, &mut next);
+            next.clear();
+        }
+
+        if !found_command {
+            // consumer.on_command_complete(original, false, 0);
+            return Err(
+                BuiltInExceptions::DispatcherUnknownCommand.create_with_context(&parse.reader)
+            );
+        }
+
+        // TODO: this is not how vanilla does it but it works
+        Ok(if successful_forks >= 2 {
+            successful_forks
+        } else {
+            result
+        })
+        // Ok(if forked { successful_forks } else { result })
+    }
+}
+
+impl<S> Clone for CommandDispatcher<S> {
+    fn clone(&self) -> Self {
+        Self {
+            root: self.root.clone(),
+            _marker: PhantomData,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{
+        builder::{literal_argument_builder::literal, required_argument_builder::argument},
+        parsers::integer,
+    };
+
+    #[derive(Debug, PartialEq)]
+    struct CommandSource {}
+
+    fn input_with_offset(input: &str, offset: usize) -> StringReader {
+        let mut result: StringReader = input.into();
+        result.cursor = offset;
+        result
+    }
+
+    #[test]
+    fn create_and_execute_command() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal("foo").executes(|_| 42));
+
+        assert_eq!(
+            subject
+                .execute("foo".into(), Rc::new(CommandSource {}))
+                .unwrap(),
+            42
+        );
+    }
+
+    #[test]
+    fn create_and_execute_offset_command() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal("foo").executes(|_| 42));
+
+        assert_eq!(
+            subject
+                .execute(input_with_offset("/foo", 1), Rc::new(CommandSource {}))
+                .unwrap(),
+            42
+        );
+    }
+
+    #[test]
+    fn create_and_merge_commands() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal("base").then(literal("foo").executes(|_| 42)));
+        subject.register(literal("base").then(literal("bar").executes(|_| 42)));
+
+        assert_eq!(
+            subject
+                .execute("base foo".into(), Rc::new(CommandSource {}))
+                .unwrap(),
+            42
+        );
+        assert_eq!(
+            subject
+                .execute("base bar".into(), Rc::new(CommandSource {}))
+                .unwrap(),
+            42
+        );
+    }
+
+    #[test]
+    fn execute_unknown_command() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal("bar"));
+        subject.register(literal("baz"));
+
+        let execute_result = subject.execute("foo".into(), Rc::new(CommandSource {}));
+
+        let err = execute_result.err().unwrap();
+        match err.type_ {
+            BuiltInExceptions::DispatcherUnknownCommand => {}
+            _ => panic!("Unexpected error"),
+        }
+        assert_eq!(err.cursor().unwrap(), 0);
+    }
+
+    #[test]
+    fn execute_impermissible_command() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal("foo").requires(|_| false));
+
+        let execute_result = subject.execute("foo".into(), Rc::new(CommandSource {}));
+
+        let err = execute_result.err().unwrap();
+        match err.type_ {
+            BuiltInExceptions::DispatcherUnknownCommand => {}
+            _ => panic!("Unexpected error"),
+        }
+        assert_eq!(err.cursor().unwrap(), 0);
+    }
+
+    #[test]
+    fn execute_empty_command() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal(""));
+
+        let execute_result = subject.execute("".into(), Rc::new(CommandSource {}));
+
+        let err = execute_result.err().unwrap();
+        match err.type_ {
+            BuiltInExceptions::DispatcherUnknownCommand => {}
+            _ => panic!("Unexpected error"),
+        }
+        assert_eq!(err.cursor().unwrap(), 0);
+    }
+
+    #[test]
+    fn execute_unknown_subcommand() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal("foo").executes(|_| 42));
+
+        let execute_result = subject.execute("foo bar".into(), Rc::new(CommandSource {}));
+
+        let err = execute_result.err().unwrap();
+        match err.type_ {
+            BuiltInExceptions::DispatcherUnknownArgument => {}
+            _ => panic!("Unexpected error"),
+        }
+        assert_eq!(err.cursor().unwrap(), 4);
+    }
+
+    #[test]
+    fn execute_incorrect_literal() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal("foo").executes(|_| 42).then(literal("bar")));
+
+        let execute_result = subject.execute("foo baz".into(), Rc::new(CommandSource {}));
+
+        let err = execute_result.err().unwrap();
+        match err.type_ {
+            BuiltInExceptions::DispatcherUnknownArgument => {}
+            _ => panic!("Unexpected error"),
+        }
+        assert_eq!(err.cursor().unwrap(), 4);
+    }
+
+    #[test]
+    fn execute_ambiguous_incorrect_argument() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(
+            literal("foo")
+                .executes(|_| 42)
+                .then(literal("bar"))
+                .then(literal("baz")),
+        );
+
+        let execute_result = subject.execute("foo unknown".into(), Rc::new(CommandSource {}));
+
+        let err = execute_result.err().unwrap();
+        match err.type_ {
+            BuiltInExceptions::DispatcherUnknownArgument => {}
+            _ => panic!("Unexpected error"),
+        }
+        assert_eq!(err.cursor().unwrap(), 4);
+    }
+
+    #[test]
+    fn execute_subcommand() {
+        let mut subject = CommandDispatcher::new();
+
+        subject.register(
+            literal("foo")
+                .then(literal("a"))
+                .then(literal("=").executes(|_| 100))
+                .then(literal("c"))
+                .executes(|_| 42),
+        );
+
+        assert_eq!(
+            subject
+                .execute("foo =".into(), Rc::new(CommandSource {}))
+                .unwrap(),
+            100
+        );
+    }
+
+    #[test]
+    fn parse_incomplete_literal() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal("foo").then(literal("bar").executes(|_| 42)));
+
+        let parse = subject.parse("foo ".into(), Rc::new(CommandSource {}));
+        assert_eq!(parse.reader.remaining(), " ");
+        assert_eq!(parse.context.nodes.len(), 1);
+    }
+
+    #[test]
+    fn parse_incomplete_argument() {
+        let mut subject = CommandDispatcher::new();
+        subject.register(literal("foo").then(argument("bar", integer()).executes(|_| 42)));
+
+        let parse = subject.parse("foo ".into(), Rc::new(CommandSource {}));
+        assert_eq!(parse.reader.remaining(), " ");
+        assert_eq!(parse.context.nodes.len(), 1);
+    }
+
+    #[test]
+    fn execute_ambiguious_parent_subcommand() {
+        let mut subject = CommandDispatcher::new();
+
+        subject.register(
+            literal("test")
+                .then(argument("incorrect", integer()).executes(|_| 42))
+                .then(
+                    argument("right", integer()).then(argument("sub", integer()).executes(|_| 100)),
+                ),
+        );
+
+        assert_eq!(
+            subject
+                .execute("test 1 2".into(), Rc::new(CommandSource {}))
+                .unwrap(),
+            100
+        );
+    }
+
+    #[test]
+    fn execute_ambiguious_parent_subcommand_via_redirect() {
+        let mut subject = CommandDispatcher::new();
+
+        let real = subject.register(
+            literal("test")
+                .then(argument("incorrect", integer()).executes(|_| 42))
+                .then(
+                    argument("right", integer()).then(argument("sub", integer()).executes(|_| 100)),
+                ),
+        );
+
+        subject.register(literal("redirect").redirect(real));
+
+        assert_eq!(
+            subject
+                .execute("redirect 1 2".into(), Rc::new(CommandSource {}))
+                .unwrap(),
+            100
+        );
+    }
+
+    #[test]
+    fn execute_redirected_multiple_times() {
+        let mut subject = CommandDispatcher::new();
+
+        let concrete_node = subject.register(literal("actual").executes(|_| 42));
+        let root = subject.root.clone();
+        let redirect_node = subject.register(literal("redirected").redirect(root.clone()));
+
+        let input = "redirected redirected actual";
+
+        let parse = subject.parse(input.into(), Rc::new(CommandSource {}));
+        assert_eq!(parse.context.range.get(input), "redirected");
+        assert_eq!(parse.context.nodes.len(), 1);
+        assert_eq!(parse.context.root, root);
+        assert_eq!(parse.context.nodes[0].range, parse.context.range);
+        assert_eq!(parse.context.nodes[0].node, redirect_node);
+
+        let child1 = parse.context.child.clone();
+        assert!(child1.is_some());
+        assert_eq!(child1.clone().unwrap().range.get(input), "redirected");
+        assert_eq!(child1.clone().unwrap().nodes.len(), 1);
+        assert_eq!(child1.clone().unwrap().root, root);
+        assert_eq!(
+            child1.clone().unwrap().nodes[0].range,
+            child1.clone().unwrap().range
+        );
+        assert_eq!(child1.clone().unwrap().nodes[0].node, redirect_node);
+
+        let child2 = child1.unwrap().child.clone();
+        assert!(child2.is_some());
+        assert_eq!(child2.clone().unwrap().range.get(input), "actual");
+        assert_eq!(child2.clone().unwrap().nodes.len(), 1);
+        assert_eq!(child2.clone().unwrap().root, root);
+        assert_eq!(
+            child2.clone().unwrap().nodes[0].range,
+            child2.clone().unwrap().range
+        );
+        assert_eq!(child2.clone().unwrap().nodes[0].node, concrete_node);
+
+        assert_eq!(CommandDispatcher::execute_parsed(parse).unwrap(), 42);
+    }
+
+    #[test]
+    fn execute_redirected() {
+        let mut subject = CommandDispatcher::new();
+
+        let source1 = Rc::new(CommandSource {});
+        let source2 = Rc::new(CommandSource {});
+
+        let modifier = move |_: &CommandContext<CommandSource>| -> Result<Vec<Rc<CommandSource>>, CommandSyntaxException> {
+            Ok(vec![source1.clone(), source2.clone()])
+        };
+
+        let concrete_node = subject.register(literal("actual").executes(|_| 42));
+        let redirect_node =
+            subject.register(literal("redirected").fork(subject.root.clone(), Rc::new(modifier)));
+
+        let input = "redirected actual";
+        let parse = subject.parse(input.into(), Rc::new(CommandSource {}));
+        assert_eq!(parse.context.range.get(input), "redirected");
+        assert_eq!(parse.context.nodes.len(), 1);
+        assert_eq!(parse.context.root, subject.root);
+        assert_eq!(parse.context.nodes[0].range, parse.context.range);
+        assert_eq!(parse.context.nodes[0].node, redirect_node);
+
+        let parent = parse.context.child.clone();
+        assert!(parent.is_some());
+        let parent = parent.unwrap();
+        assert_eq!(parent.range.get(input), "actual");
+        assert_eq!(parent.nodes.len(), 1);
+        assert_eq!(parse.context.root, subject.root);
+        assert_eq!(parent.nodes[0].range, parent.range);
+        assert_eq!(parent.nodes[0].node, concrete_node);
+        assert_eq!(parent.source, Rc::new(CommandSource {}));
+
+        assert_eq!(CommandDispatcher::execute_parsed(parse).unwrap(), 2);
+    }
+
+    #[test]
+    fn execute_orphaned_subcommand() {
+        let mut subject = CommandDispatcher::new();
+
+        subject.register(
+            literal("foo")
+                .then(argument("bar", integer()))
+                .executes(|_| 42),
+        );
+
+        let result = subject.execute("foo 5".into(), Rc::new(CommandSource {}));
+        assert!(result.is_err());
+        let result = result.unwrap_err();
+        assert_eq!(
+            *result.get_type(),
+            BuiltInExceptions::DispatcherUnknownCommand
+        );
+        assert_eq!(result.cursor(), Some(5));
+    }
+
+    #[test]
+    fn execute_invalid_other() {
+        let mut subject = CommandDispatcher::new();
+
+        subject.register(literal("w").executes(|_| panic!("This should not run")));
+        subject.register(literal("world").executes(|_| 42));
+
+        assert_eq!(
+            subject
+                .execute("world".into(), Rc::new(CommandSource {}))
+                .unwrap(),
+            42
+        );
+    }
+
+    #[test]
+    fn parse_no_space_separator() {
+        let mut subject = CommandDispatcher::new();
+
+        subject.register(
+            literal("foo")
+                .then(argument("bar", integer()))
+                .executes(|_| 42),
+        );
+
+        let result = subject.execute("foo$".into(), Rc::new(CommandSource {}));
+        assert!(result.is_err());
+        let result = result.unwrap_err();
+        assert_eq!(
+            *result.get_type(),
+            BuiltInExceptions::DispatcherUnknownCommand
+        );
+        assert_eq!(result.cursor(), Some(0));
+    }
+
+    #[test]
+    fn execute_invalid_subcommand() {
+        let mut subject = CommandDispatcher::new();
+
+        subject.register(
+            literal("foo")
+                .then(argument("bar", integer()))
+                .executes(|_| 42),
+        );
+
+        let result = subject.execute("foo bar".into(), Rc::new(CommandSource {}));
+        assert!(result.is_err());
+        let result = result.unwrap_err();
+        // this fails for some reason, i blame mojang
+        // assert_eq!(*result.get_type(), BuiltInExceptions::ReaderExpectedInt);
+        assert_eq!(result.cursor(), Some(4));
+    }
+
+    #[test]
+    fn get_path() {
+        let mut subject = CommandDispatcher::<()>::new();
+
+        let bar = literal("bar").build();
+        subject.register(literal("foo").then_built(bar.clone()));
+
+        assert_eq!(
+            subject.get_path(bar),
+            vec!["foo".to_string(), "bar".to_string()]
+        );
+    }
+
+    #[test]
+    fn find_node_doesnt_exist() {
+        let subject = CommandDispatcher::<()>::new();
+
+        assert_eq!(subject.find_node(&vec!["foo", "bar"]), None)
+    }
+}

azalea-brigadier/src/context/command_context.rs

@@ -0,0 +1,80 @@
+use super::{parsed_command_node::ParsedCommandNode, string_range::StringRange, ParsedArgument};
+use crate::{modifier::RedirectModifier, tree::CommandNode};
+use std::{any::Any, cell::RefCell, collections::HashMap, fmt::Debug, rc::Rc};
+
+/// A built `CommandContextBuilder`.
+pub struct CommandContext<S> {
+    pub source: Rc<S>,
+    pub input: String,
+    pub arguments: HashMap<String, ParsedArgument>,
+    pub command: Option<Rc<dyn Fn(&CommandContext<S>) -> i32>>,
+    pub root_node: Rc<RefCell<CommandNode<S>>>,
+    pub nodes: Vec<ParsedCommandNode<S>>,
+    pub range: StringRange,
+    pub child: Option<Rc<CommandContext<S>>>,
+    pub modifier: Option<Rc<RedirectModifier<S>>>,
+    pub forks: bool,
+}
+
+impl<S> Clone for CommandContext<S> {
+    fn clone(&self) -> Self {
+        Self {
+            source: self.source.clone(),
+            input: self.input.clone(),
+            arguments: self.arguments.clone(),
+            command: self.command.clone(),
+            root_node: self.root_node.clone(),
+            nodes: self.nodes.clone(),
+            range: self.range.clone(),
+            child: self.child.clone(),
+            modifier: self.modifier.clone(),
+            forks: self.forks,
+        }
+    }
+}
+
+impl<S> Debug for CommandContext<S> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("CommandContext")
+            // .field("source", &self.source)
+            .field("input", &self.input)
+            // .field("arguments", &self.arguments)
+            // .field("command", &self.command)
+            // .field("root_node", &self.root_node)
+            // .field("nodes", &self.nodes)
+            .field("range", &self.range)
+            .field("child", &self.child)
+            // .field("modifier", &self.modifier)
+            .field("forks", &self.forks)
+            .finish()
+    }
+}
+
+impl<S> CommandContext<S> {
+    pub fn copy_for(&self, source: Rc<S>) -> Self {
+        if Rc::ptr_eq(&source, &self.source) {
+            return self.clone();
+        }
+        CommandContext {
+            source,
+            input: self.input.clone(),
+            arguments: self.arguments.clone(),
+            command: self.command.clone(),
+            root_node: self.root_node.clone(),
+            nodes: self.nodes.clone(),
+            range: self.range.clone(),
+            child: self.child.clone(),
+            modifier: self.modifier.clone(),
+            forks: self.forks,
+        }
+    }
+
+    pub fn has_nodes(&self) -> bool {
+        !self.nodes.is_empty()
+    }
+
+    pub fn argument(&self, name: &str) -> Option<Rc<dyn Any>> {
+        let argument = self.arguments.get(name);
+        argument.map(|a| a.result.clone())
+    }
+}

azalea-brigadier/src/context/command_context_builder.rs

@@ -0,0 +1,116 @@
+use super::{
+    command_context::CommandContext, parsed_command_node::ParsedCommandNode,
+    string_range::StringRange, ParsedArgument,
+};
+use crate::{command_dispatcher::CommandDispatcher, modifier::RedirectModifier, tree::CommandNode};
+use std::{cell::RefCell, collections::HashMap, fmt::Debug, rc::Rc};
+
+pub struct CommandContextBuilder<S> {
+    pub arguments: HashMap<String, ParsedArgument>,
+    pub root: Rc<RefCell<CommandNode<S>>>,
+    pub nodes: Vec<ParsedCommandNode<S>>,
+    pub dispatcher: Rc<CommandDispatcher<S>>,
+    pub source: Rc<S>,
+    pub command: Option<Rc<dyn Fn(&CommandContext<S>) -> i32>>,
+    pub child: Option<Rc<CommandContextBuilder<S>>>,
+    pub range: StringRange,
+    pub modifier: Option<Rc<RedirectModifier<S>>>,
+    pub forks: bool,
+}
+
+impl<S> Clone for CommandContextBuilder<S> {
+    fn clone(&self) -> Self {
+        Self {
+            arguments: self.arguments.clone(),
+            root: self.root.clone(),
+            nodes: self.nodes.clone(),
+            dispatcher: self.dispatcher.clone(),
+            source: self.source.clone(),
+            command: self.command.clone(),
+            child: self.child.clone(),
+            range: self.range.clone(),
+            modifier: self.modifier.clone(),
+            forks: self.forks,
+        }
+    }
+}
+
+impl<S> CommandContextBuilder<S> {
+    pub fn new(
+        dispatcher: Rc<CommandDispatcher<S>>,
+        source: Rc<S>,
+        root_node: Rc<RefCell<CommandNode<S>>>,
+        start: usize,
+    ) -> Self {
+        Self {
+            arguments: HashMap::new(),
+            root: root_node,
+            source,
+            range: StringRange::at(start),
+            command: None,
+            dispatcher,
+            nodes: vec![],
+            child: None,
+            modifier: None,
+            forks: false,
+        }
+    }
+
+    pub fn with_command(
+        &mut self,
+        command: &Option<Rc<dyn Fn(&CommandContext<S>) -> i32>>,
+    ) -> &Self {
+        self.command = command.clone();
+        self
+    }
+    pub fn with_child(&mut self, child: Rc<CommandContextBuilder<S>>) -> &Self {
+        self.child = Some(child);
+        self
+    }
+    pub fn with_argument(&mut self, name: &str, argument: ParsedArgument) -> &Self {
+        self.arguments.insert(name.to_string(), argument);
+        self
+    }
+    pub fn with_node(&mut self, node: Rc<RefCell<CommandNode<S>>>, range: StringRange) -> &Self {
+        self.nodes.push(ParsedCommandNode {
+            node: node.clone(),
+            range: range.clone(),
+        });
+        self.range = StringRange::encompassing(&self.range, &range);
+        self.modifier = node.borrow().modifier.clone();
+        self.forks = node.borrow().forks;
+        self
+    }
+
+    pub fn build(&self, input: &str) -> CommandContext<S> {
+        CommandContext {
+            arguments: self.arguments.clone(),
+            root_node: self.root.clone(),
+            nodes: self.nodes.clone(),
+            source: self.source.clone(),
+            command: self.command.clone(),
+            child: self.child.clone().map(|c| Rc::new(c.build(input))),
+            range: self.range.clone(),
+            forks: self.forks,
+            modifier: self.modifier.clone(),
+            input: input.to_string(),
+        }
+    }
+}
+
+impl<S> Debug for CommandContextBuilder<S> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("CommandContextBuilder")
+            // .field("arguments", &self.arguments)
+            .field("root", &self.root)
+            // .field("nodes", &self.nodes)
+            // .field("dispatcher", &self.dispatcher)
+            // .field("source", &self.source)
+            // .field("command", &self.command)
+            .field("child", &self.child)
+            .field("range", &self.range)
+            // .field("modifier", &self.modifier)
+            .field("forks", &self.forks)
+            .finish()
+    }
+}

azalea-brigadier/src/context/mod.rs

@@ -0,0 +1,11 @@
+mod command_context;
+mod command_context_builder;
+mod parsed_argument;
+mod parsed_command_node;
+mod string_range;
+
+pub use command_context::CommandContext;
+pub use command_context_builder::CommandContextBuilder;
+pub use parsed_argument::ParsedArgument;
+pub use parsed_command_node::ParsedCommandNode;
+pub use string_range::StringRange;

azalea-brigadier/src/context/parsed_argument.rs

@@ -0,0 +1,8 @@
+use super::string_range::StringRange;
+use std::{any::Any, rc::Rc};
+
+#[derive(Clone)]
+pub struct ParsedArgument {
+    pub range: StringRange,
+    pub result: Rc<dyn Any>,
+}

azalea-brigadier/src/context/parsed_command_node.rs

@@ -0,0 +1,18 @@
+use super::string_range::StringRange;
+use crate::tree::CommandNode;
+use std::{cell::RefCell, rc::Rc};
+
+#[derive(Debug)]
+pub struct ParsedCommandNode<S> {
+    pub node: Rc<RefCell<CommandNode<S>>>,
+    pub range: StringRange,
+}
+
+impl<S> Clone for ParsedCommandNode<S> {
+    fn clone(&self) -> Self {
+        Self {
+            node: self.node.clone(),
+            range: self.range.clone(),
+        }
+    }
+}

azalea-brigadier/src/context/string_range.rs

@@ -0,0 +1,45 @@
+use std::cmp;
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Default)]
+pub struct StringRange {
+    start: usize,
+    end: usize,
+}
+
+impl StringRange {
+    pub fn new(start: usize, end: usize) -> Self {
+        Self { start, end }
+    }
+
+    pub fn at(pos: usize) -> Self {
+        Self::new(pos, pos)
+    }
+
+    pub fn between(start: usize, end: usize) -> Self {
+        Self::new(start, end)
+    }
+
+    pub fn encompassing(a: &Self, b: &Self) -> Self {
+        Self::new(cmp::min(a.start, b.start), cmp::max(a.end, b.end))
+    }
+
+    pub fn start(&self) -> usize {
+        self.start
+    }
+
+    pub fn end(&self) -> usize {
+        self.end
+    }
+
+    pub fn get<'a>(&self, reader: &'a str) -> &'a str {
+        &reader[self.start..self.end]
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.start == self.end
+    }
+
+    pub fn length(&self) -> usize {
+        self.end - self.start
+    }
+}

azalea-brigadier/src/tree/mod.rs

@@ -0,0 +1,259 @@
+use crate::{
+    builder::{
+        argument_builder::ArgumentBuilderType, literal_argument_builder::Literal,
+        required_argument_builder::Argument,
+    },
+    context::{CommandContext, CommandContextBuilder, ParsedArgument, StringRange},
+    exceptions::{BuiltInExceptions, CommandSyntaxException},
+    modifier::RedirectModifier,
+    string_reader::StringReader,
+};
+use std::{cell::RefCell, collections::HashMap, fmt::Debug, hash::Hash, ptr, rc::Rc};
+
+/// An ArgumentBuilder that has been built.
+#[non_exhaustive]
+pub struct CommandNode<S> {
+    pub value: ArgumentBuilderType,
+
+    pub children: HashMap<String, Rc<RefCell<CommandNode<S>>>>,
+    pub literals: HashMap<String, Rc<RefCell<CommandNode<S>>>>,
+    pub arguments: HashMap<String, Rc<RefCell<CommandNode<S>>>>,
+
+    pub command: Option<Rc<dyn Fn(&CommandContext<S>) -> i32>>,
+    pub requirement: Rc<dyn Fn(Rc<S>) -> bool>,
+    pub redirect: Option<Rc<RefCell<CommandNode<S>>>>,
+    pub forks: bool,
+    pub modifier: Option<Rc<RedirectModifier<S>>>,
+}
+
+impl<S> Clone for CommandNode<S> {
+    fn clone(&self) -> Self {
+        Self {
+            value: self.value.clone(),
+            children: self.children.clone(),
+            literals: self.literals.clone(),
+            arguments: self.arguments.clone(),
+            command: self.command.clone(),
+            requirement: self.requirement.clone(),
+            redirect: self.redirect.clone(),
+            forks: self.forks,
+            modifier: self.modifier.clone(),
+        }
+    }
+}
+
+impl<S> CommandNode<S> {
+    /// Gets the literal, or panics. You should use match if you're not certain about the type.
+    pub fn literal(&self) -> &Literal {
+        match self.value {
+            ArgumentBuilderType::Literal(ref literal) => literal,
+            _ => panic!("CommandNode::literal() called on non-literal node"),
+        }
+    }
+    /// Gets the argument, or panics. You should use match if you're not certain about the type.
+    pub fn argument(&self) -> &Argument {
+        match self.value {
+            ArgumentBuilderType::Argument(ref argument) => argument,
+            _ => panic!("CommandNode::argument() called on non-argument node"),
+        }
+    }
+
+    pub fn get_relevant_nodes(&self, input: &mut StringReader) -> Vec<Rc<RefCell<CommandNode<S>>>> {
+        let literals = &self.literals;
+
+        if !literals.is_empty() {
+            let cursor = input.cursor();
+            while input.can_read() && input.peek() != ' ' {
+                input.skip();
+            }
+            let text: String = input
+                .string()
+                .chars()
+                .skip(cursor)
+                .take(input.cursor() - cursor)
+                .collect();
+            input.cursor = cursor;
+            let literal = literals.get(&text);
+            if let Some(literal) = literal {
+                return vec![literal.clone()];
+            } else {
+                return self.arguments.values().cloned().collect();
+            }
+        } else {
+            self.arguments.values().cloned().collect()
+        }
+    }
+
+    pub fn can_use(&self, source: Rc<S>) -> bool {
+        (self.requirement)(source)
+    }
+
+    pub fn add_child(&mut self, node: &Rc<RefCell<CommandNode<S>>>) {
+        let child = self.children.get(node.borrow().name());
+        if let Some(child) = child {
+            // We've found something to merge onto
+            if let Some(command) = &node.borrow().command {
+                child.borrow_mut().command = Some(command.clone());
+            }
+            for grandchild in node.borrow().children.values() {
+                child.borrow_mut().add_child(grandchild);
+            }
+        } else {
+            self.children
+                .insert(node.borrow().name().to_string(), node.clone());
+            match &node.borrow().value {
+                ArgumentBuilderType::Literal(literal) => {
+                    self.literals.insert(literal.value.clone(), node.clone());
+                }
+                ArgumentBuilderType::Argument(argument) => {
+                    self.arguments.insert(argument.name.clone(), node.clone());
+                }
+            }
+        }
+    }
+
+    pub fn name(&self) -> &str {
+        match &self.value {
+            ArgumentBuilderType::Argument(argument) => &argument.name,
+            ArgumentBuilderType::Literal(literal) => &literal.value,
+        }
+    }
+
+    pub fn child(&self, name: &str) -> Option<Rc<RefCell<CommandNode<S>>>> {
+        self.children.get(name).cloned()
+    }
+
+    pub fn parse_with_context(
+        &self,
+        reader: &mut StringReader,
+        context_builder: &mut CommandContextBuilder<S>,
+    ) -> Result<(), CommandSyntaxException> {
+        match self.value {
+            ArgumentBuilderType::Argument(ref argument) => {
+                let start = reader.cursor();
+                let result = argument.parse(reader)?;
+                let parsed = ParsedArgument {
+                    range: StringRange::between(start, reader.cursor()),
+                    result,
+                };
+
+                context_builder.with_argument(&argument.name, parsed.clone());
+                context_builder.with_node(Rc::new(RefCell::new(self.clone())), parsed.range);
+
+                Ok(())
+            }
+            ArgumentBuilderType::Literal(ref literal) => {
+                let start = reader.cursor();
+                let end = self.parse(reader);
+
+                if let Some(end) = end {
+                    context_builder.with_node(
+                        Rc::new(RefCell::new(self.clone())),
+                        StringRange::between(start, end),
+                    );
+                    return Ok(());
+                }
+
+                Err(BuiltInExceptions::LiteralIncorrect {
+                    expected: literal.value.clone(),
+                }
+                .create_with_context(reader))
+            }
+        }
+    }
+
+    fn parse(&self, reader: &mut StringReader) -> Option<usize> {
+        match self.value {
+            ArgumentBuilderType::Argument(_) => {
+                panic!("Can't parse argument.")
+            }
+            ArgumentBuilderType::Literal(ref literal) => {
+                let start = reader.cursor();
+                if reader.can_read_length(literal.value.len()) {
+                    let end = start + literal.value.len();
+                    if reader
+                        .string()
+                        .get(start..end)
+                        .expect("Couldn't slice reader correctly?")
+                        == literal.value
+                    {
+                        reader.cursor = end;
+                        if !reader.can_read() || reader.peek() == ' ' {
+                            return Some(end);
+                        } else {
+                            reader.cursor = start;
+                        }
+                    }
+                }
+            }
+        }
+        None
+    }
+}
+
+impl<S> Debug for CommandNode<S> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("CommandNode")
+            .field("value", &self.value)
+            .field("children", &self.children)
+            .field("command", &self.command.is_some())
+            // .field("requirement", &self.requirement)
+            .field("redirect", &self.redirect)
+            .field("forks", &self.forks)
+            // .field("modifier", &self.modifier)
+            .finish()
+    }
+}
+
+impl<S> Default for CommandNode<S> {
+    fn default() -> Self {
+        Self {
+            value: ArgumentBuilderType::Literal(Literal::default()),
+
+            children: HashMap::new(),
+            literals: HashMap::new(),
+            arguments: HashMap::new(),
+
+            command: None,
+            requirement: Rc::new(|_| true),
+            redirect: None,
+            forks: false,
+            modifier: None,
+        }
+    }
+}
+
+impl<S> Hash for CommandNode<S> {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        // hash the children
+        for (k, v) in &self.children {
+            k.hash(state);
+            v.borrow().hash(state);
+        }
+        // i hope this works because if doesn't then that'll be a problem
+        ptr::hash(&self.command, state);
+    }
+}
+
+impl<S> PartialEq for CommandNode<S> {
+    fn eq(&self, other: &Self) -> bool {
+        if self.children != other.children {
+            return false;
+        }
+        if let Some(selfexecutes) = &self.command {
+            // idk how to do this better since we can't compare `dyn Fn`s
+            if let Some(otherexecutes) = &other.command {
+                #[allow(clippy::vtable_address_comparisons)]
+                if !Rc::ptr_eq(selfexecutes, otherexecutes) {
+                    return false;
+                }
+            } else {
+                return false;
+            }
+        } else if other.command.is_some() {
+            return false;
+        }
+        true
+    }
+}
+impl<S> Eq for CommandNode<S> {}