From 73067fcc1f70a990de9ec4df05d4a6e07ac6668e Mon Sep 17 00:00:00 2001
From: Garritt McCune <glmccune@gmail.com>
Date: Wed, 23 Mar 2022 19:43:46 +0000
Subject: [PATCH] Added statements to the Parser, currently just the Print and
 Expression statements. 8.1 isn't quite done yet, maybe half way there.

---
 src/lox.c       |  3 ++-
 src/parser.c    | 34 +++++++++++++++++++++++++++++++++-
 src/parser.h    |  1 +
 src/statement.c | 21 +++++++++++++++++++++
 src/statement.h | 22 ++++++++++++++++++++++
 5 files changed, 79 insertions(+), 2 deletions(-)
 create mode 100644 src/statement.c
 create mode 100644 src/statement.h

diff --git a/src/lox.c b/src/lox.c
index d1cf93a..b63d491 100644
--- a/src/lox.c
+++ b/src/lox.c
@@ -39,8 +39,9 @@ void RunFile(const char* path) {
     char* contents = GetFileContents(path);
     TokenList* tokens = ScanTokens(contents);
     free(contents);
+    printf("TOKENS:\n");
     Print(tokens);
-    printf("TREE:\n");
+    printf("EXPRESSION TREE:\n");
     Expr* tree = GenerateExpressionTree(tokens);
     PrintExpressionTree(tree);
     printf("\n");
diff --git a/src/parser.c b/src/parser.c
index e8ffa69..10093ae 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -1,5 +1,6 @@
 #include "parser.h"
 #include "expr.h"
+#include "statement.h"
 #include "token.h"
 #include <stdio.h>
 
@@ -10,6 +11,9 @@ Expr* Term(void);
 Expr* Factor(void);
 Expr* Unary(void);
 Expr* Primary(void);
+Stmt* Statement(void);
+Stmt* PrintStatement(void);
+Stmt* ExpressionStatement(void);
 int Match(int, ...);
 int Check(TokenType);
 int ParserAtEnd(void);
@@ -32,6 +36,34 @@ Expr* Expression() {
     return Equality();
 }
 
+Stmt* Statement(void) {
+    if (Match(1, PRINT)) return PrintStatement();
+
+    return ExpressionStatement();
+}
+
+Stmt* PrintStatement(void) {
+    Expr* value = Expression();
+
+    if (!Match(1, Semicolon)) fprintf(stderr, "Expected ';' after value\n");
+
+    AdvanceParser();
+
+    return CreateStatement(value, STMT_Print);
+}
+
+Stmt* ExpressionStatement(void) {
+    Expr* expr = Expression();
+
+    if (!Match(1, Semicolon)) fprintf(stderr, "Expected ';' after expression\n");
+
+    AdvanceParser();
+
+    return CreateStatement(expr, STMT_Expression);
+}
+
+Stmt* ExpressionStatement(void);
+
 Expr* Equality() {
     Expr* expr = Comparison();
 
@@ -146,7 +178,7 @@ Expr* Primary() {
         return temp;
     }
 
-    printf("Bad expression\n");
+    fprintf(stderr, "Bad expression, this should be unreachable.\n");
 
     return NULL;
 }
diff --git a/src/parser.h b/src/parser.h
index 9cb9d80..d66e67b 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -4,6 +4,7 @@
 #include "expr.h"
 #include "scanner.h"
 #include "token.h"
+#include "statement.h"
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/statement.c b/src/statement.c
new file mode 100644
index 0000000..92f3144
--- /dev/null
+++ b/src/statement.c
@@ -0,0 +1,21 @@
+#include "statement.h"
+
+Stmt* CreateStatement(Expr* expression, StatementType type) {
+    Stmt* stmt = calloc(1, sizeof(Stmt));
+
+    if (!stmt) {
+        fprintf(stderr, "Failed to calloc space for Statement. %s.\n", strerror(errno));
+        return NULL;
+    }
+
+    stmt->expression = expression;
+    stmt->type = type;
+
+    return stmt;
+}
+
+void FreeStatement(Stmt* stmt) {
+    if (!stmt) return;
+    
+    free(stmt);
+}
\ No newline at end of file
diff --git a/src/statement.h b/src/statement.h
new file mode 100644
index 0000000..bfcea8b
--- /dev/null
+++ b/src/statement.h
@@ -0,0 +1,22 @@
+#ifndef STATEMENT_H
+#define STATEMENT_H
+
+#include "expr.h"
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+typedef enum {
+    STMT_Expression,
+    STMT_Print
+} StatementType;
+
+typedef struct stmt {
+    StatementType type;
+    Expr* expression;
+} Stmt;
+
+Stmt* CreateStatement(Expr*, StatementType);
+void FreeStatement(Stmt*);
+
+#endif
\ No newline at end of file