From 4143259eb3df16470dc2d93371e65e53d027243b Mon Sep 17 00:00:00 2001
From: Tom Willemse
Date: Mon, 2 Aug 2021 18:35:10 -0700
Subject: Chapter 16.2

---
 clox/src/compiler.c | 18 ++++++++++++++++-
 clox/src/scanner.c  | 29 +++++++++++++++++++++++++++
 clox/src/scanner.h  | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 102 insertions(+), 1 deletion(-)

diff --git a/clox/src/compiler.c b/clox/src/compiler.c
index 71961ef..2cc2ee4 100644
--- a/clox/src/compiler.c
+++ b/clox/src/compiler.c
@@ -4,4 +4,20 @@
 #include "compiler.h"
 #include "scanner.h"
 
-void compile(const char *source) { initScanner(source); }
+void compile(const char *source) {
+  initScanner(source);
+  int line = -1;
+  for (;;) {
+    Token token = scanToken();
+    if (token.line != line) {
+      printf("%4d ", token.line);
+      line = token.line;
+    } else {
+      printf("   | ");
+    }
+    printf("%2d '%.*s'\n", token.type, token.length, token.start);
+
+    if (token.type == TOKEN_EOF)
+      break;
+  }
+}
diff --git a/clox/src/scanner.c b/clox/src/scanner.c
index 2bcabb8..e125a99 100644
--- a/clox/src/scanner.c
+++ b/clox/src/scanner.c
@@ -17,3 +17,32 @@ void initScanner(const char *source) {
   scanner.current = source;
   scanner.line = 1;
 }
+
+static bool isAtEnd() { return *scanner.current == '\0'; }
+
+static Token makeToken(TokenType type) {
+  Token token;
+  token.type = type;
+  token.start = scanner.start;
+  token.length = (int)(scanner.current - scanner.start);
+  token.line = scanner.line;
+  return token;
+}
+
+static Token errorToken(const char *message) {
+  Token token;
+  token.type = TOKEN_ERROR;
+  token.start = message;
+  token.length = (int)strlen(message);
+  token.line = scanner.line;
+  return token;
+}
+
+Token scanToken() {
+  scanner.start = scanner.current;
+
+  if (isAtEnd())
+    return makeToken(TOKEN_EOF);
+
+  return errorToken("Unexpected character.");
+}
diff --git a/clox/src/scanner.h b/clox/src/scanner.h
index 3b8a261..6f42a9e 100644
--- a/clox/src/scanner.h
+++ b/clox/src/scanner.h
@@ -1,6 +1,62 @@
 #ifndef SCANNER_H
 #define SCANNER_H
 
+typedef enum {
+  /* Single-character tokens. */
+  TOKEN_LEFT_PAREN,
+  TOKEN_RIGHT_PAREN,
+  TOKEN_LEFT_BRACE,
+  TOKEN_RIGHT_BRACE,
+  TOKEN_COMMA,
+  TOKEN_DOT,
+  TOKEN_MINUS,
+  TOKEN_PLUS,
+  TOKEN_SEMICOLON,
+  TOKEN_SLASH,
+  TOKEN_STAR,
+  /* One || two character tokens. */
+  TOKEN_BANG,
+  TOKEN_BANG_EQUAL,
+  TOKEN_EQUAL,
+  TOKEN_EQUAL_EQUAL,
+  TOKEN_GREATER,
+  TOKEN_GREATER_EQUAL,
+  TOKEN_LESS,
+  TOKEN_LESS_EQUAL,
+  /* Literals. */
+  TOKEN_IDENTIFIER,
+  TOKEN_STRING,
+  TOKEN_NUMBER,
+  /* Keywords. */
+  TOKEN_AND,
+  TOKEN_CLASS,
+  TOKEN_ELSE,
+  TOKEN_FALSE,
+  TOKEN_FOR,
+  TOKEN_FUN,
+  TOKEN_IF,
+  TOKEN_NIL,
+  TOKEN_OR,
+  TOKEN_PRINT,
+  TOKEN_RETURN,
+  TOKEN_SUPER,
+  TOKEN_THIS,
+  TOKEN_TRUE,
+  TOKEN_VAR,
+  TOKEN_WHILE,
+
+  TOKEN_ERROR,
+  TOKEN_EOF
+} TokenType;
+
+typedef struct {
+  TokenType type;
+  const char *start;
+  int length;
+  int line;
+} Token;
+
 void initScanner(const char *source);
+Token scanToken();
 
 #endif
-- 
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