add Scope

src/visitor/constant_folder.rs

@@ -1,4 +1,5 @@
 mod expression_reducer;
+mod scope;
 
 use full_moon::ast::*;
 
@@ -86,7 +87,6 @@ impl Visitor for ConstantFolder {
     fn visit_local_assignment<'a>(&mut self, local_assignment: &LocalAssignment<'a>) {
         let mut names = local_assignment.names().iter();
         let mut expressions = local_assignment.expressions().iter();
-
         loop {
             let name = names.next().map(|x| x.token().to_string());
             let expr = expressions.next().map(|x| x.clone() /* reduced */);

src/visitor/constant_folder/scope.rs

@@ -0,0 +1,48 @@
+use crate::visitor::constant_folder::expression_reducer::Variable;
+
+type Local = Vec<Variable>;
+
+pub struct Scope {
+    scope: Vec<Local>,
+}
+
+impl Scope {
+    pub fn new() -> Self {
+        Self {
+            scope: vec![],
+        }
+    }
+
+    fn frame(&self) -> Option<&Local> {
+        self.scope.last()
+    }
+
+    fn frame_mut(&mut self) -> Option<&mut Local> {
+        self.scope.last_mut()
+    }
+
+    pub fn new_frame(&mut self) {
+        self.scope.push(vec![])
+    }
+
+    pub fn push_var(&mut self, var: Variable) {
+        self.frame_mut().map(|frame| frame.push(var));
+    }
+
+    pub fn find_name(&self, name: String) -> Option<&Variable> {
+        self.frame().map_or(None, |frame| {
+            frame
+                .iter()
+                .find(|var| var.name() == name)
+        })
+    }
+
+    pub fn set_var(&mut self, value: Variable) {
+        self.frame_mut().map(|frame| {
+            frame
+                .iter_mut()
+                .find(|var| var.name() == value.name())
+                .map(|var| var.assign_value(value))
+        });
+    }
+}

src/visitor/constant_folder/variable_.rs

@@ -1,144 +0,0 @@
-/// A compile-time expression folder (constant propagation)
-///
-/// To do constant folding, we must be able to reduce expression at
-/// the compile-time. We give each Variable an Expression and reduce it.
-/// If there is some expression, the variable value is the expression reduced.
-/// Else the variable has undefined value at compile-time.
-///
-/// We try to reduce
-/// ```lua
-/// L41_1 = L37_1
-/// L42_1 = 20
-/// L43_1 = 76
-/// L44_1 = 201
-/// L45_1 = 132
-/// L46_1 = 98
-/// L47_1 = 93
-/// L41_1 = (L41_1(L42_1, L43_1, L44_1, L45_1, L46_1, L47_1))
-/// ```
-/// into
-/// ```lua
-/// L41_1 = L37_1
-/// L42_1 = 20
-/// L43_1 = 76
-/// L44_1 = 201
-/// L45_1 = 132
-/// L46_1 = 98
-/// L47_1 = 93
-/// L41_1 = L37_1(20, 76, 201, 132, 98, 93)
-/// ```
-///
-/// We reduce expression with a list of local variables.
-///
-/// There are many cases where reduction fail to complete, these expression
-/// won't reduced and kept the same.
-///
-/// - Undefined or parameter
-/// - Nil initialized
-/// - Set {}
-/// - For counter
-///
-/// Every expression containing these won't be reduced furthur. Thus:
-/// ```lua
-/// L1 = 0
-/// L2 = nil
-/// L3 = L1 + L2
-/// ```
-/// reduces into
-/// ```lua
-/// L1 = 0
-/// L2 = nil
-/// L3 = 0 + L2
-/// ```
-///
-/// Keep in mind that we do expression folding only, dead code elimination
-/// is done through another pass
-use std::ops;
-
-enum BinOp {
-    Plus,
-    Minus,
-    Modulus,
-    Times,
-    Dividend,
-    Concat,
-}
-
-enum CompareOp {
-    Lt,
-    Eq,
-    Gt,
-    Lte,
-    Gte,
-    Ne,
-}
-
-/// Types of expression
-enum Expression {
-    /// a number (int)
-    Literal(i64),
-    /// a string literal
-    String(String),
-    /// special name of library module.function (math.min)
-    Module(String, Vec<String>),
-    /// variable referencing
-    Var(Variable),
-    /// Binary operation between expression
-    BinOp(Box<Expression>, Box<Expression>, BinOp),
-    /// Index into array
-    Index(Box<Expression>, Box<Expression>),
-    /// Comparision expression (1 < 2)
-    Comparision(Box<Expression>, Box<Expression>, CompareOp),
-    /// Function call
-    FunctionCall(),
-}
-
-/// Variable has a name and the expression attached to it
-pub struct Variable {
-    name: String,
-    value: Option<Box<Expression>>,
-}
-
-impl Expression {
-}
-
-impl ops::Add for Expression {
-    type Output = Self;
-    fn add(self, other: Self) -> Self {
-        
-    }
-}
-impl ops::Sub for Expression {}
-impl ops::Mul for Expression {}
-impl ops::Div for Expression {}
-impl ops::Rem for Expression {}
-
-pub fn reduce_expression(expr: Expression, locals: Vec<Variable>) -> Expression {
-    match expr {
-        Expression::BinOp(lhs_, rhs_, op) => {
-            let lhs = reduce_expression(*lhs_, locals);
-            let rhs = reduce_expression(*rhs_, locals);
-            match op {
-                Plus => {
-                    lhs + rhs
-                }
-                Minus => {
-                    lhs - rhs
-                }
-                Modulus => {
-                    lhs % rhs
-                }
-                Times => {
-                    lhs * rhs
-                }
-                Dividend => {
-                    lhs / rhs
-                }
-                Concat => {
-                    lhs.concat(rhs)
-                }
-            }
-        }
-        _ => expr
-    }
-}

very_small.lua

@@ -1,22 +1,3 @@
--- local L1_1, L1_2, L41_1, L42_1, L43_1, L44_1, L45_1, L46_1, L47_1, L37_1
--- L1_2 = 2
--- L1_1 = 1 + L1_2
--- L1_1 = true
--- L1_2 = false
--- L1_1 = L1_1 and L1_2
-
--- L41_1 = L37_1
--- L42_1 = 20
--- L43_1 = 76
--- L44_1 = 201
--- L45_1 = 132
--- L46_1 = 98
--- L47_1 = 93
--- L41_1 = (L41_1(L42_1, L43_1, L44_1, L45_1, L46_1, L47_1))
-
--- L1_1 = math
--- L1_1 = math.min
-
 local L0_1, L1_1, L2_1, L3_1, L4_1, L5_1, L6_1, L7_1, L8_1, L9_1, L10_1, L11_1, L12_1, L13_1, L14_1, L15_1, L16_1, L17_1, L18_1, L19_1, L20_1, L21_1, L22_1, L23_1, L24_1, L25_1, L26_1, L27_1, L28_1, L29_1, L30_1, L31_1, L32_1, L33_1, L34_1, L35_1, L36_1, L37_1, L38_1, L39_1, L40_1, L41_1, L42_1, L43_1, L44_1, L45_1, L46_1, L47_1, L48_1, L49_1, L50_1, L51_1, L52_1, L53_1, L54_1, L55_1, L56_1, L57_1, L58_1, L59_1, L60_1, L61_1, L62_1, L63_1, L64_1, L65_1, L66_1, L67_1, L68_1, L69_1, L70_1, L71_1, L72_1, L73_1, L74_1, L75_1, L76_1, L77_1, L78_1, L79_1, L80_1, L81_1, L82_1, L83_1, L84_1, L85_1, L86_1, L87_1, L88_1, L89_1, L90_1, L91_1, L92_1, L93_1, L94_1, L95_1, L96_1, L97_1, L98_1, L99_1, L100_1, L101_1, L102_1, L103_1, L104_1, L105_1, L106_1, L107_1, L108_1, L109_1, L110_1, L111_1, L112_1, L113_1, L114_1, L115_1, L116_1, L117_1, L118_1, L119_1, L120_1, L121_1, L122_1, L123_1, L124_1, L125_1, L126_1, L127_1, L128_1, L129_1, L130_1, L131_1, L132_1, L133_1, L134_1, L135_1, L136_1, L137_1, L138_1, L139_1, L140_1, L141_1, L142_1, L143_1, L144_1, L145_1, L146_1, L147_1, L148_1, L149_1, L150_1, L151_1, L152_1, L153_1, L154_1, L155_1, L156_1, L157_1, L158_1, L159_1, L160_1, L161_1, L162_1, L163_1, L164_1, L165_1, L166_1, L167_1, L168_1, L169_1, L170_1, L171_1, L172_1, L173_1, L174_1, L175_1, L176_1, L177_1, L178_1, L179_1, L180_1, L181_1, L182_1, L183_1, L184_1, L185_1, L186_1, L187_1, L188_1, L189_1, L190_1, L191_1, L192_1, L193_1, L194_1, L195_1, L196_1, L197_1, L198_1, L199_1, L200_1, L201_1, L202_1, L203_1, L204_1, L205_1, L206_1, L207_1, L208_1, L209_1, L210_1, L211_1, L212_1, L213_1, L214_1, L215_1, L216_1, L217_1, L218_1, L219_1, L220_1, L221_1, L222_1, L223_1, L224_1, L225_1, L226_1, L227_1, L228_1, L229_1, L230_1
 L1_1 = math
 L1_1 = L1_1.fmod
@@ -46,3 +27,18 @@ L13_1 = string
 L13_1 = L13_1.len
 L14_1 = string
 L14_1 = L14_1.gsub
+
+L1_2 = 2
+L1_1 = 1 + L1_2
+L1_1 = true
+L1_2 = false
+L1_1 = L1_1 and L1_20
+
+L41_1 = L37_1
+L42_1 = 20
+L43_1 = 76
+L44_1 = 201
+L45_1 = 132
+L46_1 = 98
+L47_1 = 93
+L41_1 = (L41_1(L42_1, L43_1, L44_1, L45_1, L46_1, L47_1))