From 19fa9bf6c7cf01221e91e934c7ac2017104e21aa Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Fri, 11 Sep 2020 15:57:17 -0400
Subject: [PATCH] Start implementing parsing numbers from strings

---
 src/bigint.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/bigint.rs b/src/bigint.rs
index 8472bb3..9145e2e 100644
--- a/src/bigint.rs
+++ b/src/bigint.rs
@@ -128,7 +128,28 @@ impl BigInt {
     /// Convert a `&str` or a `String` representing a number in the specified radix to a Bigint.
     ///
     /// For radix 10, use the `from` associated function instead.
+    ///
+    /// Radix must be between 1 and 36, inclusive, with radix higher
+    /// than 11 represented by A-Z
+    ///
+    /// Only alphanumeric characters are considered, so exponents and
+    /// other forms are not parsed
     pub fn from_str_radix<T: ToString>(s: T, radix: usize) -> BigInt {
+        let input = s.to_string();
+
+        // Convert each digit to it's decimal representation
+        let mut raw_digits: Vec<usize> = Vec::with_capacity(input.len());
+        for maybe_digit in input.chars() {
+            match maybe_digit.to_digit(radix as u32) {
+                Some(d) => raw_digits.push(d as usize),
+                None => continue,
+            }
+        }
+
+        // Calculate the decimal value by calculating the value
+        // of each place value
+
+        // In base 1, number of place values = total value
         todo!();
     }