From b1794edb3d76db7c1a86fc14a60bc95b833bc7c7 Mon Sep 17 00:00:00 2001
From: Frederick Yin <fkfd@fkfd.me>
Date: Sat, 3 Sep 2022 11:22:20 +0800
Subject: hackc: more statements; UnexpectedToken

---
 projects/hackc/statements.py | 156 ++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 148 insertions(+), 8 deletions(-)

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

diff --git a/projects/hackc/statements.py b/projects/hackc/statements.py
index 16c123e..0e257ed 100644
--- a/projects/hackc/statements.py
+++ b/projects/hackc/statements.py
@@ -1,19 +1,42 @@
-from .expressions import Expression
+from .expressions import Expression, SubroutineCall
 from .utils import *
 
+
 class Statement:
     def __init__(self):
         pass
 
     @classmethod
     def from_tokens(cls, tokens: list) -> tuple:
-        for StatementClass in [LetStatement]:
+        for StatementClass in [LetStatement, DoStatement, ReturnStatement, IfStatement]:
             stmt, dt = StatementClass.from_tokens(tokens)
             if stmt is not None:
                 return (stmt, dt)
 
         return (None, 0)
 
+
+class StatementList:
+    def __init__(self, statements: list[Statement]):
+        self.statements = statements
+
+    @classmethod
+    def from_tokens(cls, tokens: list) -> tuple:
+        t = 0
+        statements = []
+        while True:
+            stmt, dt = Statement.from_tokens(tokens[t:])
+            if stmt is None:
+                break
+            statements.append(stmt)
+            t += dt
+        return (StatementList(statements), t)
+
+    def print_verbose(self):
+        for stmt in self.statements:
+            stmt.print_verbose()
+
+
 class LetStatement:
     def __init__(self, name, expr):
         self.name = name
@@ -31,22 +54,139 @@ class LetStatement:
 
         name = tokens[1]
         if name.type != "identifier":
-            raise JackSyntaxError(f"Expected variable name, got `{name}` instead", name)
+            raise UnexpectedToken("variable name", name)
 
         if tokens[2] != "=":
-            raise JackSyntaxError(f"Expected `=`, got `{tokens[2]}` instead", tokens[2])
+            raise UnexpectedToken("=", tokens[2])
 
         t = 3
         expr, dt = Expression.from_tokens(tokens[t:])
         if expr is None:
-            raise JackSyntaxError(f"Expected expression", tokens[3])
+            raise UnexpectedToken(f"Expected expression", tokens[3])
         t += dt
 
         if tokens[t] != ";":
-            raise JackSyntaxError(f"Expected `;`, got `{tokens[t]}` instead", tokens[t])
+            raise UnexpectedToken(";", tokens[t])
 
-        t += 1
-        return (LetStatement(name, expr), t)
+        return (LetStatement(name, expr), t + 1)
 
     def print_verbose(self):
         print(f"Let {self.name} be {self.expr}")
+
+
+class DoStatement:
+    def __init__(self, subcall: SubroutineCall):
+        self.subcall = subcall
+
+    @classmethod
+    def from_tokens(cls, tokens: list) -> tuple:
+        """Construct do statement.
+
+        Format:
+        'do' <subroutine call> ';'
+        """
+        if len(tokens) < 5 or tokens[0] != "do":
+            return (None, 0)
+
+        t = 1
+        subcall, dt = SubroutineCall.from_tokens(tokens[1:])
+        if subcall is None:
+            raise UnexpectedToken("subroutine call", tokens[1])
+        t += dt
+
+        if tokens[t] != ";":
+            raise UnexpectedToken(";", tokens[t])
+
+        return (DoStatement(subcall), t + 1)
+
+    def print_verbose(self):
+        print(f"Do {self.subcall}")
+
+
+class ReturnStatement:
+    def __init__(self, expr: Expression):
+        self.expr = expr
+
+    @classmethod
+    def from_tokens(cls, tokens: list) -> tuple:
+        """Construct return statement.
+
+        Format:
+        'return' <expression>? ';'
+        """
+        if len(tokens) < 3 or tokens[0] != "return":
+            return (None, 0)
+
+        t = 1
+        expr, dt = Expression.from_tokens(tokens[1:])
+        t += dt
+
+        if tokens[t] != ";":
+            raise UnexpectedToken(";", tokens[t])
+
+        return (ReturnStatement(expr), t + 1)
+
+    def print_verbose(self):
+        print(f"Return {self.expr or 'null'}")
+
+
+class IfStatement:
+    def __init__(self, condition: Expression, then: StatementList, else_then=None):
+        self.condition = condition
+        self.then = then
+        self.else_then = else_then
+
+    @classmethod
+    def from_tokens(cls, tokens: list) -> tuple:
+        """Construct if statement.
+
+        Format:
+        'if' '(' <expression> ')' '{' <statement list> '}' ('else' '{' <statement list '}')?
+        """
+        if len(tokens) < 6 or tokens[0] != "if":
+            return (None, 0)
+
+        if tokens[1] != LEFT_PAREN:
+            raise UnexpectedToken(LEFT_PAREN, tokens[1])
+
+        t = 2
+        cond, dt = Expression.from_tokens(tokens[2:])
+        if cond is None:
+            raise JackSyntaxError(f"Expected condition", tokens[2])
+        t += dt
+
+        if tokens[t] != RIGHT_PAREN:
+            raise UnexpectedToken(RIGHT_PAREN, tokens[t])
+        if tokens[t + 1] != LEFT_BRACE:
+            raise UnexpectedToken(LEFT_BRACE, tokens[t + 1])
+        t += 2
+
+        then, dt = StatementList.from_tokens(tokens[t:])
+        t += dt
+
+        if tokens[t] != RIGHT_BRACE:
+            raise UnexpectedToken(RIGHT_BRACE, tokens[t])
+        t += 1
+
+        if tokens[t] != "else":
+            return (IfStatement(cond, then), t)
+
+        if tokens[t + 1] != LEFT_BRACE:
+            raise UnexpectedToken(LEFT_BRACE, tokens[t + 1])
+
+        t += 2
+
+        else_then, dt = StatementList.from_tokens(tokens[t:])
+        t += dt
+
+        if tokens[t] != RIGHT_BRACE:
+            raise UnexpectedToken(RIGHT_BRACE, tokens[t])
+
+        return (IfStatement(cond, then, else_then), t + 1)
+
+    def print_verbose(self):
+        print(f"If {self.condition} then:")
+        self.then.print_verbose()
+        if self.else_then is not None:
+            print("Else then:")
+            self.else_then.print_verbose()
-- 
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