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/expressions.py | 96 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 79 insertions(+), 17 deletions(-)

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

diff --git a/projects/hackc/expressions.py b/projects/hackc/expressions.py
index f4623da..2e08cef 100644
--- a/projects/hackc/expressions.py
+++ b/projects/hackc/expressions.py
@@ -24,9 +24,7 @@ class Term:
             """Format: '(' <expression> ')'"""
             expr, dt = Expression.from_tokens(tokens[1:])
             if tokens[dt + 1] != RIGHT_PAREN:
-                raise JackSyntaxError(
-                    f"Expected `{RIGHT_PAREN}`, got `{tokens[dt]}` instead", tokens[dt]
-                )
+                raise UnaryTerm(RIGHT_PAREN, tokens[dt])
             return (expr, dt + 2)
         if tokens[0].type == "identifier":
             if tokens[1] in [LEFT_PAREN, "."]:
@@ -69,9 +67,7 @@ class SubscriptTerm:
             raise JackSyntaxError(f"Expected subscript", tokens[2])
         t += dt
         if tokens[t] != RIGHT_BRACKET:
-            raise JackSyntaxError(
-                f"Expected `{RIGHT_BRACKET}`, got `{tokens[t]}` instead", tokens[t]
-            )
+            raise UnexpectedToken(RIGHT_BRACKET, tokens[t])
         return (SubscriptTerm(var, sub), t + 1)
 
     def __str__(self):
@@ -95,16 +91,6 @@ class UnaryTerm:
         return f"({self.op}{self.term})"
 
 
-class SubroutineCall:
-    def __init__(self, name: Token, exprs: list):
-        self.name = name
-        self.exprs = exprs
-
-    @classmethod
-    def from_tokens(cls, tokens: list) -> tuple:
-        pass
-
-
 class Expression:
     def __init__(self, lhs: Term, op=None, rhs=None):
         self.lhs = lhs
@@ -119,6 +105,8 @@ class Expression:
         <term> (<op> <term>)?
         """
         lhs, dt = Term.from_tokens(tokens)
+        if lhs is None:
+            return (None, 0)
         t = dt
 
         op = tokens[t]
@@ -128,7 +116,7 @@ class Expression:
         t += 1
         rhs, dt = Term.from_tokens(tokens[t:])
         if rhs is None:
-            raise JSE(f"Expected other term, got `{rhs}` instead", rhs)
+            raise UnexpectedToken("other term", rhs)
         t += dt
 
         return (Expression(lhs, op, rhs), t)
@@ -138,3 +126,77 @@ class Expression:
             return f"({self.lhs} {self.op} {self.rhs})"
         else:
             return str(self.lhs)
+
+
+class ExpressionList:
+    def __init__(self, exprs: list[Expression]):
+        self.exprs = exprs
+
+    @classmethod
+    def from_tokens(cls, tokens: list) -> tuple:
+        """Construct list of expressions.
+
+        Format:
+        (<expression> (',' <expression>)*)?
+        """
+        t = 0
+        exprs = []
+        while True:
+            expr, dt = Expression.from_tokens(tokens[t:])
+            if expr is None:
+                if t == 0:
+                    # only allow lack of expression right after paren
+                    break
+                else:
+                    # expect expression after comma
+                    raise JackSyntaxError(f"Expected expression", tokens[t])
+            t += dt
+            exprs.append(expr)
+            if tokens[t] != ",":
+                break
+            t += 1
+
+        return (ExpressionList(exprs), t)
+
+    def __str__(self):
+        return ", ".join([str(expr) for expr in self.exprs])
+
+
+class SubroutineCall:
+    def __init__(self, jack_class: Token, name: Token, exprs: ExpressionList):
+        self.jack_class = jack_class
+        self.name = name
+        self.exprs = exprs
+
+    @classmethod
+    def from_tokens(cls, tokens: list) -> tuple:
+        """Construct invocation of subroutine.
+
+        Format:
+        (<class> '.')? <subroutine> '(' <expression list> ')'
+        """
+        t = 0
+        jack_class = None
+        if tokens[1] == ".":
+            jack_class = tokens[0]
+            t = 2
+
+        name = tokens[t]
+        if name.type != "identifier":
+            raise UnexpectedToken("subroutine name", name)
+        t += 1
+
+        if tokens[t] != LEFT_PAREN:
+            raise UnexpectedToken(LEFT_PAREN, tokens[t])
+        t += 1
+
+        exprs, dt = ExpressionList.from_tokens(tokens[t:])
+        t += dt
+        if tokens[t] != RIGHT_PAREN:
+            raise UnexpectedToken(RIGHT_PAREN, tokens[t])
+        return (SubroutineCall(jack_class, name, exprs), t + 1)
+
+    def __str__(self):
+        if self.jack_class is None:
+            return f"{self.name}({self.exprs})"
+        return f"{self.jack_class}.{self.name}({self.exprs})"
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