POC comptime optimizations

vic1707 · Oct 16, 2023 · 1d40aff · 1d40aff
1 parent e37f403
commit 1d40aff
Show file tree

Hide file tree

Showing 4 changed files with 221 additions and 2 deletions.
diff --git a/Cargo.toml b/Cargo.toml
@@ -14,6 +14,7 @@ name = "repl"
 path = "src/bin/repl.rs"
 
 [features]
-default = ["pemdas"]
+default = ["pemdas", "compile-time-optimizations"]
 pemdas = []
 pejmdas = []
+compile-time-optimizations = []
diff --git a/src/element/comp_time.rs b/src/element/comp_time.rs
@@ -0,0 +1,211 @@
+use super::{BinOp, Element, FunctionCall, UnOp};
+use crate::token::Operator;
+
+pub trait CompTime<'a> {
+    fn simplify(self) -> Element<'a>;
+}
+
+impl<'a> CompTime<'a> for Element<'a> {
+    #[inline]
+    fn simplify(self) -> Self {
+        match self {
+            Self::BinOp(binop) => binop.simplify(),
+            Self::UnOp(unop) => unop.simplify(),
+            Self::Function(func) => func.simplify(),
+            Self::Number(_) | Self::Variable(_) => self,
+        }
+    }
+}
+
+impl<'a> CompTime<'a> for BinOp<'a> {
+    #[inline]
+    #[allow(clippy::too_many_lines)]
+    fn simplify(self) -> Element<'a> {
+        use Element::Number;
+        use Operator::{Divide, Minus, Modulo, Plus, Power, Times};
+        match self {
+            /////////////////////////// Additions ///////////////////////////
+            // 0 + .. => ..
+            BinOp { op: Plus, lhs, rhs } if lhs == Number(0.0_f64) => {
+                rhs.simplify()
+            },
+            // .. + 0 => ..
+            BinOp { op: Plus, lhs, rhs } if rhs == Number(0.0_f64) => {
+                lhs.simplify()
+            },
+            ////////////////////////// Subtractions /////////////////////////
+            // 0 - .. => -..
+            BinOp {
+                op: Minus,
+                lhs,
+                rhs,
+            } if lhs == Number(0.0_f64) => {
+                UnOp::new(Operator::Minus, rhs.simplify()).simplify()
+            },
+            // .. - 0 => ..
+            BinOp {
+                op: Minus,
+                lhs,
+                rhs,
+            } if rhs == Number(0.0_f64) => lhs.simplify(),
+            // .. - .. => 0
+            BinOp {
+                op: Minus,
+                lhs,
+                rhs,
+            } if lhs == rhs => Number(0.0_f64),
+            //////////////////////// Multiplications ////////////////////////
+            // 0 * .. => 0
+            BinOp { op: Times, lhs, .. } if lhs == Number(0.0_f64) => {
+                Number(0.0_f64)
+            },
+            // .. * 0 => 0
+            BinOp { op: Times, rhs, .. } if rhs == Number(0.0_f64) => {
+                Number(0.0_f64)
+            },
+            // 1 * .. => ..
+            BinOp {
+                op: Times,
+                lhs,
+                rhs,
+            } if lhs == Number(1.0_f64) => rhs.simplify(),
+            // .. * 1 => ..
+            BinOp {
+                op: Times,
+                lhs,
+                rhs,
+            } if rhs == Number(1.0_f64) => lhs.simplify(),
+            /////////////////////////// Divisions ///////////////////////////
+            // 0 / .. => 0
+            BinOp {
+                op: Divide, lhs, ..
+            } if lhs == Number(0.0_f64) => Number(0.0_f64),
+            // .. / 0 => inf
+            BinOp {
+                op: Divide, rhs, ..
+            } if rhs == Number(0.0_f64) => Number(f64::INFINITY),
+            // .. / 1 => ..
+            BinOp {
+                op: Divide,
+                lhs,
+                rhs,
+            } if rhs == Number(1.0_f64) => lhs.simplify(),
+            // .. / .. => 1
+            BinOp {
+                op: Divide,
+                lhs,
+                rhs,
+            } if lhs == rhs => Number(1.0_f64),
+            ///////////////////////////// Powers ////////////////////////////
+            // 0 ^ .. => 0
+            BinOp { op: Power, lhs, .. } if lhs == Number(0.0_f64) => {
+                Number(0.0_f64)
+            },
+            // .. ^ 0 => 1
+            BinOp {
+                op: Divide, rhs, ..
+            } if rhs == Number(0.0_f64) => Number(1.0_f64),
+            // .. ^ 1 => ..
+            BinOp {
+                op: Power,
+                lhs,
+                rhs,
+            } if rhs == Number(1.0_f64) => lhs.simplify(),
+            //////////////////////////// Modulos ////////////////////////////
+            // 0 % .. => 0
+            BinOp {
+                op: Modulo, lhs, ..
+            } if lhs == Number(0.0_f64) => Number(0.0_f64),
+            // .. % 0 => NaN
+            BinOp {
+                op: Modulo, rhs, ..
+            } if rhs == Number(0.0_f64) => Number(f64::NAN),
+            // .. % 1 => 0
+            BinOp {
+                op: Modulo, rhs, ..
+            } if rhs == Number(1.0_f64) => Number(0.0_f64),
+            // .. % .. => 0
+            BinOp {
+                op: Modulo,
+                lhs,
+                rhs,
+            } if lhs == rhs => Number(0.0_f64),
+            // other
+            BinOp {
+                op,
+                rhs: Number(rhs),
+                lhs: Number(lhs),
+            } => {
+                let result = match op {
+                    Plus => lhs + rhs,
+                    Minus => lhs - rhs,
+                    Times => lhs * rhs,
+                    Divide => lhs / rhs,
+                    Power => lhs.powf(rhs),
+                    #[allow(clippy::modulo_arithmetic)]
+                    Modulo => lhs % rhs,
+                };
+                Number(result)
+            },
+            BinOp { op, rhs, lhs } => Element::BinOp(Box::new(BinOp::new(
+                op,
+                lhs.simplify(),
+                rhs.simplify(),
+            ))),
+        }
+    }
+}
+
+impl<'a> CompTime<'a> for UnOp<'a> {
+    #[inline]
+    fn simplify(self) -> Element<'a> {
+        let operand = self.operand.simplify();
+        #[allow(clippy::unreachable)]
+        match self.op {
+            Operator::Plus => operand,
+            Operator::Minus => match operand {
+                Element::Number(num) => Element::Number(-num),
+                Element::UnOp(unop) => match unop.op {
+                    Operator::Plus => Element::UnOp(Box::new(UnOp::new(
+                        Operator::Minus,
+                        unop.operand,
+                    ))),
+                    Operator::Minus => unop.operand,
+                    Operator::Times
+                    | Operator::Divide
+                    | Operator::Power
+                    | Operator::Modulo => unreachable!(),
+                },
+                Element::BinOp(_)
+                | Element::Function(_)
+                | Element::Variable(_) => Element::UnOp(Box::new(UnOp {
+                    op: self.op,
+                    operand,
+                })),
+            },
+            Operator::Times
+            | Operator::Divide
+            | Operator::Power
+            | Operator::Modulo => unreachable!(),
+        }
+    }
+}
+
+impl<'a> CompTime<'a> for FunctionCall<'a> {
+    #[inline]
+    fn simplify(self) -> Element<'a> {
+        let arg = self.arg.simplify();
+        match arg {
+            Element::Number(num) => Element::Number((self.func)(num)),
+            Element::BinOp(_)
+            | Element::UnOp(_)
+            | Element::Function(_)
+            | Element::Variable(_) => {
+                Element::Function(Box::new(FunctionCall {
+                    func: self.func,
+                    arg,
+                }))
+            },
+        }
+    }
+}
diff --git a/src/element/mod.rs b/src/element/mod.rs
@@ -2,10 +2,12 @@
 use core::fmt;
 /* Modules */
 mod binop;
+mod comp_time;
 mod function_call;
 mod unop;
 /* Exports */
 pub use binop::BinOp;
+pub use comp_time::CompTime;
 pub use function_call::FunctionCall;
 pub use unop::UnOp;
 

diff --git a/src/parser.rs b/src/parser.rs
@@ -6,7 +6,7 @@ use std::collections::HashSet;
 /* Crate imports */
 use crate::{
     context::Context,
-    element::{BinOp, Element, FunctionCall, UnOp},
+    element::{BinOp, CompTime, Element, FunctionCall, UnOp},
     macros::{trust_me, yeet},
     token::{Identifier, Operator},
     utils::precedence,
@@ -112,6 +112,11 @@ impl<'a> ParserImpl<'a> {
             el = Element::BinOp(Box::new(BinOp::new(op, el, rhs)));
         }
 
+        #[cfg(feature = "compile-time-optimizations")]
+        {
+            el = el.simplify();
+        };
+
         Ok(el)
     }