1 files changed, 242 insertions, 0 deletions
diff --git a/codegen/src/ext.rs b/codegen/src/ext.rs
new file mode 100644
index 0000000..3a08935
--- /dev/null
+++ b/codegen/src/ext.rs
@@ -0,0 +1,242 @@
+use syntex::Registry;
+
+use syntex_syntax::ast::{ExprKind, MetaItem, Arm, Expr, PatKind, LitKind, Pat};
+use syntex_syntax::codemap::Span;
+use syntex_syntax::ext::base::{Annotatable, ExtCtxt, MacEager, MacResult, DummyResult};
+use syntex_syntax::ext::build::AstBuilder;
+use syntex_syntax::parse::token::{Token, InternedString, DelimToken};
+use syntex_syntax::parse::parser::Parser;
+use syntex_syntax::parse::PResult;
+use syntex_syntax::ptr::P;
+use syntex_syntax::tokenstream::TokenTree;
+
+use definitions::{State, Action};
+
+pub fn register(registry: &mut Registry) {
+    registry.add_macro("state_table", expand_state_table);
+}
+
+fn state_from_str<S>(s: &S) -> Result<State, ()>
+    where S: AsRef<str>
+{
+    Ok(match s.as_ref() {
+        "State::Anywhere" => State::Anywhere,
+        "State::CsiEntry" => State::CsiEntry,
+        "State::CsiIgnore" => State::CsiIgnore,
+        "State::CsiIntermediate" => State::CsiIntermediate,
+        "State::CsiParam" => State::CsiParam,
+        "State::DcsEntry" => State::DcsEntry,
+        "State::DcsIgnore" => State::DcsIgnore,
+        "State::DcsIntermediate" => State::DcsIntermediate,
+        "State::DcsParam" => State::DcsParam,
+        "State::DcsPassthrough" => State::DcsPassthrough,
+        "State::Escape" => State::Escape,
+        "State::EscapeIntermediate" => State::EscapeIntermediate,
+        "State::Ground" => State::Ground,
+        "State::OscString" => State::OscString,
+        "State::SosPmApcString" => State::SosPmApcString,
+        _ => return Err(())
+    })
+}
+
+fn parse_table_input_mappings<'a>(parser: &mut Parser<'a>) -> PResult<'a, Vec<Arm>> {
+    // Must start on open brace
+    try!(parser.expect(&Token::OpenDelim(DelimToken::Brace)));
+
+    let mut arms: Vec<Arm> = Vec::new();
+    while parser.token != Token::CloseDelim(DelimToken::Brace) {
+        match parser.parse_arm() {
+            Ok(arm) => arms.push(arm),
+            Err(mut e) => {
+                // Recover by skipping to the end of the block.
+                return Err(e);
+            }
+        }
+    }
+
+    // Consume the closing brace
+    parser.bump();
+    Ok(arms)
+}
+
+/// Expressions describing state transitions and actions
+#[derive(Debug)]
+struct TableDefinitionExprs {
+    state_expr: P<Expr>,
+    mapping_arms: Vec<Arm>,
+}
+
+fn state_from_expr(expr: P<Expr>, cx: &mut ExtCtxt) -> Result<State, ()> {
+    let s = match expr.node {
+        ExprKind::Path(ref _qself, ref path) => {
+            path.to_string()
+        },
+        _ => {
+            cx.span_err(expr.span, "expected State");
+            return Err(())
+        }
+    };
+
+    state_from_str(&s).map_err(|_| {
+        cx.span_err(expr.span, "expected State");
+        ()
+    })
+}
+
+fn u8_lit_from_expr(expr: &Expr, cx: &mut ExtCtxt) -> Result<u8, ()> {
+    static MSG: &'static str = "expected u8 int literal";
+
+    match expr.node {
+        ExprKind::Lit(ref lit) => {
+            match lit.node {
+                LitKind::Int(val, _) => {
+                    Ok(val as u8)
+                },
+                _ => {
+                    cx.span_err(lit.span, MSG);
+                    return Err(());
+                }
+            }
+        },
+        _ => {
+            cx.span_err(expr.span, MSG);
+            return Err(());
+        }
+    }
+}
+
+fn input_mapping_from_arm(arm: Arm, cx: &mut ExtCtxt) -> Result<InputMapping, ()> {
+    let Arm { pats, body, .. } = arm;
+
+    let input = try!(InputDefinition::from_pat(&pats[0], cx));
+    let transition = try!(Transition::from_expr(&body, cx));
+
+    Ok(InputMapping {
+        input: input,
+        transition: transition,
+    })
+}
+
+/// What happens when certain input is received
+enum Transition {
+    State(State),
+    Action(Action),
+    StateAction(State, Action),
+}
+
+impl Transition {
+    fn from_expr(expr: &Expr, cx: &mut ExtCtxt) -> Result<Transition, ()> {
+        unimplemented!();
+    }
+}
+
+enum InputDefinition {
+    Specific(u8),
+    Range { start: u8, end: u8 }
+}
+
+impl InputDefinition {
+    fn from_pat(pat: &Pat, cx: &mut ExtCtxt) -> Result<InputDefinition, ()> {
+        Ok(match pat.node {
+            PatKind::Lit(ref lit_expr) => {
+                InputDefinition::Specific(try!(u8_lit_from_expr(&lit_expr, cx)))
+            },
+            PatKind::Range(ref start_expr, ref end_expr) => {
+                InputDefinition::Range {
+                    start: try!(u8_lit_from_expr(start_expr, cx)),
+                    end: try!(u8_lit_from_expr(end_expr, cx)),
+                }
+            },
+            _ => {
+                cx.span_err(pat.span, "expected literal or range expression");
+                return Err(())
+            }
+        })
+    }
+}
+
+struct InputMapping {
+    input: InputDefinition,
+    transition: Transition,
+}
+
+struct TableDefinition {
+    state: State,
+    mappings: Vec<InputMapping>,
+}
+
+fn parse_raw_definitions(
+    definitions: Vec<TableDefinitionExprs>,
+    cx: &mut ExtCtxt
+) -> Result<Vec<TableDefinition>, ()> {
+    let mut out = Vec::new();
+
+    for raw in definitions {
+        let TableDefinitionExprs { state_expr, mapping_arms } = raw;
+        let state = try!(state_from_expr(state_expr, cx));
+
+        let mut mappings = Vec::new();
+        for arm in mapping_arms {
+            mappings.push(try!(input_mapping_from_arm(arm, cx)));
+        }
+
+        out.push(TableDefinition {
+            state: state,
+            mappings: mappings,
+        })
+    }
+
+    Ok(out)
+}
+
+fn parse_table_definition<'a>(parser: &mut Parser<'a>) -> PResult<'a, TableDefinitionExprs> {
+    let state_expr = try!(parser.parse_expr());
+    try!(parser.expect(&Token::FatArrow));
+    let mappings = try!(parse_table_input_mappings(parser));
+
+    Ok(TableDefinitionExprs {
+        state_expr: state_expr,
+        mapping_arms: mappings
+    })
+}
+
+fn parse_table_definition_list<'a>(parser: &mut Parser<'a>)
+    -> PResult<'a, Vec<TableDefinitionExprs>>
+{
+    let mut definitions = Vec::new();
+    while parser.token != Token::Eof {
+        definitions.push(try!(parse_table_definition(parser)));
+        parser.eat(&Token::Comma);
+    }
+
+    Ok(definitions)
+}
+
+fn expand_state_table<'cx>(
+    cx: &'cx mut ExtCtxt,
+    sp: Span,
+    args: &[TokenTree])
+    -> Box<MacResult + 'cx>
+{
+    macro_rules! ptry {
+        ($pres:expr) => {
+            match $pres {
+                Ok(val) => val,
+                Err(mut err) => {
+                    err.emit();
+                    return DummyResult::any(sp);
+                }
+            }
+        }
+    }
+
+    // Parse the lookup spec
+    let mut parser: Parser = cx.new_parser_from_tts(args);
+    let definitions = ptry!(parse_table_definition_list(&mut parser));
+    let definitions = match parse_raw_definitions(definitions, cx) {
+        Ok(definitions) => definitions,
+        Err(_) => return DummyResult::any(sp),
+    };
+
+    panic!("End of current implementation, go write some more :)");
+}