From 69aa7b493da7a0536199ed4a69c734567ab6cbfc Mon Sep 17 00:00:00 2001
From: Luna <git@l4.pm>
Date: Fri, 31 May 2019 22:08:41 -0300
Subject: [PATCH] add number tokens

---
 src/main.zig    |  3 +++
 src/scanner.zig | 53 ++++++++++++++++++++++++++++++++++++++++++++++++-
 src/token.zig   |  2 ++
 3 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/src/main.zig b/src/main.zig
index 3423204..807041d 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -21,6 +21,9 @@ fn run(allocator: *Allocator, data: []u8) !void {
             .Slice => |value| {
                 try value.printToken(stdout);
             },
+            .Number => |value| {
+                try value.printToken(stdout);
+            },
         }
 
         hadError = false;
diff --git a/src/scanner.zig b/src/scanner.zig
index 8bbc5a8..051a98f 100644
--- a/src/scanner.zig
+++ b/src/scanner.zig
@@ -5,6 +5,10 @@ const main = @import("main.zig");
 
 const TokenList = std.ArrayList(token.Token);
 
+fn isDigit(char: u8) bool {
+    return char >= '0' and char <= '9';
+}
+
 pub const Scanner = struct {
     source: []u8,
     tokens: TokenList,
@@ -55,6 +59,18 @@ pub const Scanner = struct {
         });
     }
 
+    /// Keep in mind Lox only has a single number type and that is a float one.
+    fn addNumberToken(self: *Scanner, ttype: token.TokenType, num: f32) !void {
+        try self.addToken(token.Token{
+            .Number = token.NumberToken.init(
+                ttype,
+                self.currentLexeme(),
+                self.line,
+                num,
+            ),
+        });
+    }
+
     fn addToken(
         self: *Scanner,
         tok: token.Token,
@@ -114,6 +130,37 @@ pub const Scanner = struct {
         );
     }
 
+    fn peekNext(self: *Scanner) u8 {
+        if (self.current + 1 >= self.source.len) return 0;
+        return self.source[self.current + 1];
+    }
+
+    /// Consume a number
+    fn doNumber(self: *Scanner) !void {
+        while (isDigit(self.peek())) {
+            _ = self.advance();
+        }
+
+        // check if its a number like 12.34, where the '.' character
+        // exists and the one next to it is a digit.
+        if (self.peek() == '.' and isDigit(self.peekNext())) {
+            _ = self.advance();
+
+            while (isDigit(self.peek())) {
+                _ = self.advance();
+            }
+        }
+
+        // after going through all of the number, we can just use fmt.parseFloat
+
+        var num = try std.fmt.parseFloat(
+            f32,
+            self.source[self.start..self.current],
+        );
+
+        try self.addNumberToken(.NUMBER, num);
+    }
+
     /// Scan through our tokens and add them to the Scanner's token list.
     fn scanToken(self: *Scanner) !void {
         var c = self.advance();
@@ -154,7 +201,11 @@ pub const Scanner = struct {
             '"' => try self.doString(),
 
             else => {
-                try main.doError(self.line, "Unexpected character");
+                if (isDigit(c)) {
+                    try self.doNumber();
+                } else {
+                    try main.doError(self.line, "Unexpected character");
+                }
             },
         }
     }
diff --git a/src/token.zig b/src/token.zig
index 4460dad..c4400a3 100644
--- a/src/token.zig
+++ b/src/token.zig
@@ -98,8 +98,10 @@ pub fn TokenFactory(
 
 pub const SimpleToken = TokenFactory(void);
 pub const SliceToken = TokenFactory([]u8);
+pub const NumberToken = TokenFactory(f32);
 
 pub const Token = union(enum) {
     Simple: SimpleToken,
     Slice: SliceToken,
+    Number: NumberToken,
 };