From e3b5457fe62f9ddabe4cbfd18d4921f1c1a8b3e1 Mon Sep 17 00:00:00 2001
From: Austen Adler <agadler@austenadler.com>
Date: Wed, 2 Jun 2021 18:50:06 -0400
Subject: [PATCH] Write vector multiplication

---
 src/calc.rs         |  4 ++--
 src/calc/entries.rs | 52 ++++++++++++++++++++++++++++++++++++++++-----
 src/calc/errors.rs  |  3 +++
 3 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/src/calc.rs b/src/calc.rs
index 426e00c..703c7b7 100644
--- a/src/calc.rs
+++ b/src/calc.rs
@@ -5,7 +5,7 @@ pub mod types;
 use crate::calc::entries::CalculatorEntry;
 
 use confy::{load, store};
-use entries::{Entry, Number, Vector};
+use entries::{Entry, Number, Vector, VectorDirection};
 use errors::{CalculatorError, CalculatorResult};
 use operations::{
     ArithmeticOperation, CalculatorOperation, CalculatorStateChange, MacroState, OpArgs,
@@ -552,7 +552,7 @@ impl Calculator {
             .unzip();
         let entry = Entry::Vector(Vector {
             values,
-            direction: true,
+            direction: VectorDirection::Row,
         });
         entries.push_front(count_entry);
         Ok(CalculatorStateChange {
diff --git a/src/calc/entries.rs b/src/calc/entries.rs
index c5b54c6..eb8d12e 100644
--- a/src/calc/entries.rs
+++ b/src/calc/entries.rs
@@ -30,9 +30,31 @@ impl PartialEq for Number {
     }
 }
 
+#[derive(PartialEq, Copy, Clone, Debug, Serialize, Deserialize)]
+pub enum VectorDirection {
+    Row,
+    Column,
+}
+
+impl VectorDirection {
+    pub fn swap(&self) -> Self {
+        match self {
+            Self::Row => Self::Column,
+            Self::Column => Self::Row,
+        }
+    }
+
+    pub fn get_separator(&self) -> &str {
+        match self {
+            Self::Row => "  ",
+            Self::Column => "; ",
+        }
+    }
+}
+
 #[derive(Clone, PartialEq, Debug, Serialize, Deserialize)]
 pub struct Vector {
-    pub direction: bool,
+    pub direction: VectorDirection,
     pub values: Vec<Number>,
 }
 
@@ -41,7 +63,7 @@ pub struct Vector {
 pub enum Entry {
     Number(Number),
     Vector(Vector),
-    // Matrix(Vec<Vec<Number>>),
+    // Matrix(Vec<Vector>),
 }
 
 // macro_rules! op_child_call {
@@ -297,7 +319,7 @@ impl CalculatorEntry for Vector {
                 .iter()
                 .map(|number| number.format_entry(display_mode))
                 .collect::<Vec<String>>()
-                .join(if self.direction { "; " } else { "  " })
+                .join(self.direction.get_separator())
         )
     }
     // Mathematical operations
@@ -316,7 +338,7 @@ impl CalculatorEntry for Vector {
     fn inverse(&self) -> CalculatorResult<Entry> {
         Ok(Entry::Vector(Vector {
             values: self.values.clone(),
-            direction: !self.direction,
+            direction: self.direction.swap(),
         }))
     }
     fn sin(&self, angle_mode: CalculatorAngleMode) -> CalculatorResult<Entry> {
@@ -397,7 +419,27 @@ impl CalculatorEntry for Vector {
         self.iterated_binary_vec(arg, Number::sub_num)
     }
     fn mul_vec(&self, arg: &Self) -> CalculatorResult<Entry> {
-        self.iterated_binary_vec(arg, Number::mul_num)
+        if self.values.len() != arg.values.len() {
+            return Err(CalculatorError::DimensionMismatch);
+        }
+        match (self.direction, arg.direction) {
+            (VectorDirection::Row, VectorDirection::Column) => {
+                // Row by column -- will produce a scalar
+                self.values
+                    .iter()
+                    .zip(arg.values.iter())
+                    .try_fold(Entry::Number(Number::ZERO), |acc, (n1, n2)| {
+                        acc.add(&n1.mul_num(n2)?)
+                    })
+            }
+            (VectorDirection::Column, VectorDirection::Row) => {
+                Err(CalculatorError::NotYetImplemented)
+            }
+            (VectorDirection::Row, VectorDirection::Row)
+            | (VectorDirection::Column, VectorDirection::Column) => {
+                Err(CalculatorError::DimensionMismatch)
+            }
+        }
     }
     fn div_vec(&self, arg: &Self) -> CalculatorResult<Entry> {
         self.iterated_binary_vec(arg, Number::div_num)
diff --git a/src/calc/errors.rs b/src/calc/errors.rs
index 7421c8a..6882f60 100644
--- a/src/calc/errors.rs
+++ b/src/calc/errors.rs
@@ -15,6 +15,8 @@ pub enum CalculatorError {
     TypeMismatch,
     /// Dimensions must match
     DimensionMismatch,
+    /// Plans are in place to implement, but we are not there yet
+    NotYetImplemented,
     /// Thrown when an undo or redo cannot be performed
     CorruptStateChange(String),
     /// Cannot undo or redo
@@ -50,6 +52,7 @@ impl fmt::Display for CalculatorError {
             Self::NotEnoughStackEntries => write!(f, "Not enough items in the stack"),
             Self::TypeMismatch => write!(f, "Type mismatch"),
             Self::DimensionMismatch => write!(f, "Dimension mismatch"),
+            Self::NotYetImplemented => write!(f, "Not yet implemented"),
             Self::CorruptStateChange(msg) => {
                 write!(f, "Corrupt state change: {}", msg)
             }