make Lexer peekable without a wrapper

1 files changed, 26 insertions, 12 deletions

diff --git a/src/Lexer.zig b/src/Lexer.zig
index 62b2352..8c23b26 100644
--- a/src/Lexer.zig
+++ b/src/Lexer.zig
@@ -44,13 +44,27 @@ pub const Location = struct {
     }
 };
 
+pub fn peek(self: *Self) Token {
+    if (self.peeked == null) {
+        self.peeked = self.getNext();
+    }
+    return self.peeked.?;
+}
+
+pub fn next(self: *Self) Token {
+    const token = self.peek();
+    self.peeked = null;
+    return token;
+}
+
 source: []const u8,
 start: usize = 0,
 pos: usize = 0,
+peeked: ?Token = null,
 
-pub fn next(self: *Self) ?Token {
+fn getNext(self: *Self) Token {
     self.start = self.pos;
-    return s: switch (self.eat() orelse return self.create(.eof)) {
+    return s: switch (self.eatChar() orelse return self.create(.eof)) {
         '(' => self.create(.left_paren),
         ')' => self.create(.right_paren),
         '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' => self.integerLiteral(),
@@ -58,7 +72,7 @@ pub fn next(self: *Self) ?Token {
         '-' => self.create(.minus),
         ' ' => {
             self.start = self.pos;
-            continue :s (self.eat() orelse return self.create(.eof));
+            continue :s (self.eatChar() orelse return self.create(.eof));
         },
         else => |c| if ('a' <= c and c <= 'z' or 'A' <= c and c <= 'Z')
             self.identifierOrKeyword()
@@ -69,7 +83,7 @@ pub fn next(self: *Self) ?Token {
 
 fn integerLiteral(self: *Self) Token {
     var value: ?u64 = self.source[self.start] - '0';
-    while (digitValue(self.peek())) |v| {
+    while (digitValue(self.peekChar())) |v| {
         var nxt: ?u64 = null;
         if (value) |val|
             if (std.math.mul(u64, val, 10) catch null) |p|
@@ -78,7 +92,7 @@ fn integerLiteral(self: *Self) Token {
                 };
 
         value = nxt;
-        _ = self.eat();
+        _ = self.eatChar();
     }
     return if (value != null)
         self.create(.integer_literal)
@@ -88,9 +102,9 @@ fn integerLiteral(self: *Self) Token {
 
 fn identifierOrKeyword(self: *Self) Token {
     while (true) {
-        const c = self.peek() orelse 0;
+        const c = self.peekChar() orelse 0;
         if ('a' <= c and c <= 'z' or 'A' <= c and c <= 'Z' or c == '_') {
-            _ = self.eat();
+            _ = self.eatChar();
             continue;
         }
         const value = self.source[self.start..self.pos];
@@ -101,18 +115,18 @@ fn identifierOrKeyword(self: *Self) Token {
     }
 }
 
-fn create(self: *Self, tajp: Token.Type) Token {
+fn create(self: *Self, ty: Token.Type) Token {
     const start = self.start;
-    return .{ .loc = .{ .start = start, .end = self.pos }, .type = tajp };
+    return .{ .loc = .{ .start = start, .end = self.pos }, .type = ty };
 }
 
-fn eat(self: *Self) ?u8 {
-    const token = self.peek();
+fn eatChar(self: *Self) ?u8 {
+    const token = self.peekChar();
     if (token != null) self.pos += 1;
     return token;
 }
 
-fn peek(self: *Self) ?u8 {
+fn peekChar(self: *Self) ?u8 {
     return if (self.pos < self.source.len) self.source[self.pos] else null;
 }