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-rw-r--r--src/com/craftinginterpreters/lox/Parser.java30
1 files changed, 29 insertions, 1 deletions
diff --git a/src/com/craftinginterpreters/lox/Parser.java b/src/com/craftinginterpreters/lox/Parser.java
index c68316f..9a9c0e6 100644
--- a/src/com/craftinginterpreters/lox/Parser.java
+++ b/src/com/craftinginterpreters/lox/Parser.java
@@ -20,7 +20,7 @@ class Parser {
List<Stmt> statements = new ArrayList<>();
while (!isAtEnd()) {
- statements.add(statement());
+ statements.add(declaration());
}
return statements;
@@ -30,6 +30,18 @@ class Parser {
return equality();
}
+ private Stmt declaration() {
+ try {
+ if (match(VAR))
+ return varDeclaration();
+
+ return statement();
+ } catch (ParseError error) {
+ synchronize();
+ return null;
+ }
+ }
+
private Stmt statement() {
if (match(PRINT))
return printStatement();
@@ -43,6 +55,18 @@ class Parser {
return new Stmt.Print(value);
}
+ private Stmt varDeclaration() {
+ Token name = consume(IDENTIFIER, "Expect variable name.");
+
+ Expr initializer = null;
+ if (match(EQUAL)) {
+ initializer = expression();
+ }
+
+ consume(SEMICOLON, "Expect ';' after variable declaration.");
+ return new Stmt.Var(name, initializer);
+ }
+
private Stmt expressionStatement() {
Expr expr = expression();
consume(SEMICOLON, "Expect ';' after expression.");
@@ -119,6 +143,10 @@ class Parser {
return new Expr.Literal(previous().literal);
}
+ if (match(IDENTIFIER)) {
+ return new Expr.Variable(previous());
+ }
+
if (match(LEFT_PAREN)) {
Expr expr = expression();
consume(RIGHT_PAREN, "Expect ')' after expression.");