From 61f3490b9e6132cbad70c90637ed349a42fe7704 Mon Sep 17 00:00:00 2001
From: Frederick Yin <fkfd@fkfd.me>
Date: Wed, 31 Aug 2022 16:42:22 +0800
Subject: hackc: i dont even remember

---
 projects/hackc/statements.py | 49 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 projects/hackc/statements.py

(limited to 'projects/hackc/statements.py')

diff --git a/projects/hackc/statements.py b/projects/hackc/statements.py
new file mode 100644
index 0000000..e8bc0b3
--- /dev/null
+++ b/projects/hackc/statements.py
@@ -0,0 +1,49 @@
+from .expressions import Expression
+
+class Statement:
+    def __init__(self):
+        pass
+
+    @classmethod
+    def from_tokens(cls, tokens: list) -> tuple:
+        for StatementClass in [LetStatement]:
+            stmt, dt = StatementClass.from_tokens(tokens)
+            if stmt is not None:
+                return (stmt, dt)
+
+        return (None, 0)
+
+class LetStatement:
+    def __init__(self, name, expr):
+        self.name = name
+        self.expr = expr
+
+    @classmethod
+    def from_tokens(cls, tokens: list) -> tuple:
+        """Construct let statement.
+
+        Format:
+        'let' <name> '=' <expression> ';'
+        """
+        if len(tokens) < 5 or tokens[0] != "let":
+            return (None, 0)
+
+        name = tokens[1]
+        if name.type != "identifier":
+            raise JackSyntaxError(f"Expected variable name, got `{name}` instead", name)
+
+        if tokens[2] != "=":
+            raise JackSyntaxError(f"Expected `=`, got `{tokens[2]}` instead", tokens[2])
+
+        t = 3
+        expr, dt = Expression.from_tokens(tokens[t:])
+        if expr is None:
+            raise JackSyntaxError(f"Expected expression", tokens[3])
+        t += dt
+
+        if tokens[t] != ";":
+            raise JackSyntaxError(f"Expected `;`, got `{tokens[t]}` instead", tokens[t])
+
+        t += 1
+        return (LetStatement(name, expr), t)
+
-- 
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