schala/schala-lang/language/src/reduced_ast.rs

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use std::rc::Rc;
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use crate::ast::*;
use crate::symbol_table::{Symbol, SymbolSpec, SymbolTable};
use crate::builtin::{BinOp, PrefixOp};
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#[derive(Debug)]
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pub struct ReducedAST(pub Vec<Stmt>);
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#[derive(Debug, Clone)]
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pub enum Stmt {
PreBinding {
name: Rc<String>,
func: Func,
},
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Binding {
name: Rc<String>,
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constant: bool,
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expr: Expr,
},
Expr(Expr),
Noop,
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}
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#[derive(Debug, Clone)]
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pub enum Expr {
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Unit,
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Lit(Lit),
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Tuple(Vec<Expr>),
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Func(Func),
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Val(Rc<String>),
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Constructor {
type_name: Rc<String>,
name: Rc<String>,
tag: usize,
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arity: usize,
},
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Call {
f: Box<Expr>,
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args: Vec<Expr>,
},
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Assign {
val: Box<Expr>,
expr: Box<Expr>,
},
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Conditional {
cond: Box<Expr>,
then_clause: Vec<Stmt>,
else_clause: Vec<Stmt>,
},
ConditionalTargetSigilValue,
CaseMatch {
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cond: Box<Expr>,
alternatives: Vec<Alternative>
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},
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UnimplementedSigilValue
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}
pub type BoundVars = Vec<Option<Rc<String>>>; //remember that order matters here
#[derive(Debug, Clone)]
pub struct Alternative {
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pub tag: Option<usize>,
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pub subpatterns: Vec<Option<Subpattern>>,
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pub guard: Option<Expr>,
pub bound_vars: BoundVars,
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pub item: Vec<Stmt>,
}
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#[derive(Debug, Clone)]
pub struct Subpattern {
pub tag: Option<usize>,
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pub subpatterns: Vec<Option<Subpattern>>,
pub bound_vars: BoundVars,
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pub guard: Option<Expr>,
}
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#[derive(Debug, Clone)]
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pub enum Lit {
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Nat(u64),
Int(i64),
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Float(f64),
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Bool(bool),
StringLit(Rc<String>),
}
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#[derive(Debug, Clone)]
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pub enum Func {
BuiltIn(Rc<String>),
UserDefined {
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name: Option<Rc<String>>,
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params: Vec<Rc<String>>,
body: Vec<Stmt>,
}
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}
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impl AST {
pub fn reduce(&self, symbol_table: &SymbolTable) -> ReducedAST {
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let mut output = vec![];
for statement in self.0.iter() {
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output.push(statement.node().reduce(symbol_table));
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}
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ReducedAST(output)
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}
}
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impl Statement {
fn reduce(&self, symbol_table: &SymbolTable) -> Stmt {
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use crate::ast::Statement::*;
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match self {
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ExpressionStatement(expr) => Stmt::Expr(expr.node().reduce(symbol_table)),
Declaration(decl) => decl.reduce(symbol_table),
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}
}
}
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fn reduce_block(block: &Block, symbol_table: &SymbolTable) -> Vec<Stmt> {
block.iter().map(|stmt| stmt.node().reduce(symbol_table)).collect()
}
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impl Expression {
fn reduce(&self, symbol_table: &SymbolTable) -> Expr {
use crate::ast::ExpressionKind::*;
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let ref input = self.0;
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match input {
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NatLiteral(n) => Expr::Lit(Lit::Nat(*n)),
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FloatLiteral(f) => Expr::Lit(Lit::Float(*f)),
StringLiteral(s) => Expr::Lit(Lit::StringLit(s.clone())),
BoolLiteral(b) => Expr::Lit(Lit::Bool(*b)),
BinExp(binop, lhs, rhs) => binop.reduce(symbol_table, lhs, rhs),
PrefixExp(op, arg) => op.reduce(symbol_table, arg),
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Value(name) => match symbol_table.lookup_by_name(name) {
Some(Symbol { spec: SymbolSpec::DataConstructor { index, type_args, type_name}, .. }) => Expr::Constructor {
type_name: type_name.clone(),
name: name.clone(),
tag: index.clone(),
arity: type_args.len(),
},
_ => Expr::Val(name.clone()),
},
Call { f, arguments } => Expr::Call {
f: Box::new(f.node().reduce(symbol_table)),
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args: arguments.iter().map(|arg| arg.node().reduce(symbol_table)).collect(),
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},
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TupleLiteral(exprs) => Expr::Tuple(exprs.iter().map(|e| e.node().reduce(symbol_table)).collect()),
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IfExpression { discriminator, body } => reduce_if_expression(discriminator, body, symbol_table),
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Lambda { params, body, .. } => reduce_lambda(params, body, symbol_table),
NamedStruct { .. } => Expr::UnimplementedSigilValue,
Index { .. } => Expr::UnimplementedSigilValue,
WhileExpression { .. } => Expr::UnimplementedSigilValue,
ForExpression { .. } => Expr::UnimplementedSigilValue,
ListLiteral { .. } => Expr::UnimplementedSigilValue,
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}
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}
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}
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fn reduce_lambda(params: &Vec<FormalParam>, body: &Block, symbol_table: &SymbolTable) -> Expr {
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Expr::Func(Func::UserDefined {
name: None,
params: params.iter().map(|param| param.0.clone()).collect(),
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body: reduce_block(body, symbol_table),
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})
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}
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fn reduce_if_expression(discriminator: &Discriminator, body: &IfExpressionBody, symbol_table: &SymbolTable) -> Expr {
let cond = Box::new(match *discriminator {
Discriminator::Simple(ref expr) => expr.reduce(symbol_table),
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Discriminator::BinOp(ref _expr, ref _binop) => panic!("Can't yet handle binop discriminators")
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});
match *body {
IfExpressionBody::SimpleConditional(ref then_clause, ref else_clause) => {
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let then_clause = reduce_block(then_clause, symbol_table);
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let else_clause = match else_clause {
None => vec![],
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Some(stmts) => reduce_block(stmts, symbol_table),
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};
Expr::Conditional { cond, then_clause, else_clause }
},
IfExpressionBody::SimplePatternMatch(ref pat, ref then_clause, ref else_clause) => {
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let then_clause = reduce_block(then_clause, symbol_table);
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let else_clause = match else_clause {
None => vec![],
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Some(stmts) => reduce_block(stmts, symbol_table),
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};
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let alternatives = vec![
pat.to_alternative(then_clause, symbol_table),
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Alternative {
tag: None,
subpatterns: vec![],
bound_vars: vec![],
guard: None,
item: else_clause
},
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];
Expr::CaseMatch {
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cond,
alternatives,
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}
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},
IfExpressionBody::GuardList(ref guard_arms) => {
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let mut alternatives = vec![];
for arm in guard_arms {
match arm.guard {
Guard::Pat(ref p) => {
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let item = reduce_block(&arm.body, symbol_table);
let alt = p.to_alternative(item, symbol_table);
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alternatives.push(alt);
},
Guard::HalfExpr(HalfExpr { op: _, expr: _ }) => {
return Expr::UnimplementedSigilValue
}
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}
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}
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Expr::CaseMatch { cond, alternatives }
}
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}
}
/* ig var pat
* x is SomeBigOldEnum(_, x, Some(t))
*/
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fn handle_symbol(symbol: Option<&Symbol>, inner_patterns: &Vec<Pattern>, symbol_table: &SymbolTable) -> Subpattern {
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use self::Pattern::*;
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let tag = symbol.map(|symbol| match symbol.spec {
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SymbolSpec::DataConstructor { index, .. } => index.clone(),
_ => panic!("Symbol is not a data constructor - this should've been caught in type-checking"),
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});
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let bound_vars = inner_patterns.iter().map(|p| match p {
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Literal(PatternLiteral::VarPattern(var)) => Some(var.clone()),
_ => None,
}).collect();
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let subpatterns = inner_patterns.iter().map(|p| match p {
Ignored => None,
Literal(PatternLiteral::VarPattern(_)) => None,
Literal(other) => Some(other.to_subpattern(symbol_table)),
tp @ TuplePattern(_) => Some(tp.to_subpattern(symbol_table)),
ts @ TupleStruct(_, _) => Some(ts.to_subpattern(symbol_table)),
Record(..) => unimplemented!(),
}).collect();
let guard = None;
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/*
let guard_equality_exprs: Vec<Expr> = subpatterns.iter().map(|p| match p {
Literal(lit) => match lit {
_ => unimplemented!()
},
_ => unimplemented!()
}).collect();
*/
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Subpattern {
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tag,
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subpatterns,
guard,
bound_vars,
}
}
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impl Pattern {
fn to_alternative(&self, item: Vec<Stmt>, symbol_table: &SymbolTable) -> Alternative {
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let s = self.to_subpattern(symbol_table);
Alternative {
tag: s.tag,
subpatterns: s.subpatterns,
bound_vars: s.bound_vars,
guard: s.guard,
item
}
}
fn to_subpattern(&self, symbol_table: &SymbolTable) -> Subpattern {
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use self::Pattern::*;
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match self {
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TupleStruct(name, inner_patterns) => {
let symbol = symbol_table.lookup_by_name(name).expect(&format!("Symbol {} not found", name));
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handle_symbol(Some(symbol), inner_patterns, symbol_table)
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},
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TuplePattern(inner_patterns) => handle_symbol(None, inner_patterns, symbol_table),
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Record(_name, _pairs) => {
unimplemented!()
},
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Ignored => Subpattern { tag: None, subpatterns: vec![], guard: None, bound_vars: vec![] },
Literal(lit) => lit.to_subpattern(symbol_table),
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}
}
}
impl PatternLiteral {
fn to_subpattern(&self, symbol_table: &SymbolTable) -> Subpattern {
use self::PatternLiteral::*;
match self {
NumPattern { neg, num } => {
let comparison = Expr::Lit(match (neg, num) {
(false, ExpressionKind::NatLiteral(n)) => Lit::Nat(*n),
(false, ExpressionKind::FloatLiteral(f)) => Lit::Float(*f),
(true, ExpressionKind::NatLiteral(n)) => Lit::Int(-1*(*n as i64)),
(true, ExpressionKind::FloatLiteral(f)) => Lit::Float(-1.0*f),
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_ => panic!("This should never happen")
});
let guard = Some(Expr::Call {
f: Box::new(Expr::Func(Func::BuiltIn(Rc::new("==".to_string())))),
args: vec![comparison, Expr::ConditionalTargetSigilValue],
});
Subpattern {
tag: None,
subpatterns: vec![],
guard,
bound_vars: vec![],
}
},
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StringPattern(s) => {
let guard = Some(Expr::Call {
f: Box::new(Expr::Func(Func::BuiltIn(Rc::new("==".to_string())))),
args: vec![Expr::Lit(Lit::StringLit(s.clone())), Expr::ConditionalTargetSigilValue]
});
Subpattern {
tag: None,
subpatterns: vec![],
guard,
bound_vars: vec![],
}
},
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BoolPattern(b) => {
let guard = Some(if *b {
Expr::ConditionalTargetSigilValue
} else {
Expr::Call {
f: Box::new(Expr::Func(Func::BuiltIn(Rc::new("!".to_string())))),
args: vec![Expr::ConditionalTargetSigilValue]
}
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});
Subpattern {
tag: None,
subpatterns: vec![],
guard,
bound_vars: vec![],
}
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},
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VarPattern(var) => match symbol_table.lookup_by_name(var) {
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Some(symbol) => handle_symbol(Some(symbol), &vec![], symbol_table),
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None => Subpattern {
tag: None,
subpatterns: vec![],
guard: None,
bound_vars: vec![Some(var.clone())],
}
}
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}
}
}
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impl Declaration {
fn reduce(&self, symbol_table: &SymbolTable) -> Stmt {
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use self::Declaration::*;
match self {
Binding {name, constant, expr, .. } => Stmt::Binding { name: name.clone(), constant: *constant, expr: expr.node().reduce(symbol_table) },
FuncDecl(Signature { name, params, .. }, statements) => Stmt::PreBinding {
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name: name.clone(),
func: Func::UserDefined {
name: Some(name.clone()),
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params: params.iter().map(|param| param.0.clone()).collect(),
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body: reduce_block(&statements, symbol_table),
}
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},
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TypeDecl { .. } => Stmt::Noop,
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TypeAlias(_, _) => Stmt::Noop,
Interface { .. } => Stmt::Noop,
Impl { .. } => Stmt::Expr(Expr::UnimplementedSigilValue),
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_ => Stmt::Expr(Expr::UnimplementedSigilValue)
}
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}
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}
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impl BinOp {
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fn reduce(&self, symbol_table: &SymbolTable, lhs: &Box<Meta<Expression>>, rhs: &Box<Meta<Expression>>) -> Expr {
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if **self.sigil() == "=" {
Expr::Assign {
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val: Box::new(lhs.node().reduce(symbol_table)),
expr: Box::new(rhs.node().reduce(symbol_table)),
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}
} else {
let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
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Expr::Call { f, args: vec![lhs.node().reduce(symbol_table), rhs.node().reduce(symbol_table)]}
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}
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}
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}
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impl PrefixOp {
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fn reduce(&self, symbol_table: &SymbolTable, arg: &Box<Meta<Expression>>) -> Expr {
let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
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Expr::Call { f, args: vec![arg.node().reduce(symbol_table)]}
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}
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}