From e88635d6d32055cc7d3a4ccf16c1a74cb5b88d1c Mon Sep 17 00:00:00 2001
From: Shagun Agrawal <agrawalshagun07@gmail.com>
Date: Thu, 22 Aug 2024 00:51:56 +0530
Subject: Add analyzer for validating program semantics

Add validator for semantic analysis

Pass ch5 test cases for validate flag
---
 src/cljcc/analyzer.clj | 90 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 88 insertions(+), 2 deletions(-)

(limited to 'src/cljcc/analyzer.clj')

diff --git a/src/cljcc/analyzer.clj b/src/cljcc/analyzer.clj
index b7d42a2..5eb03ee 100644
--- a/src/cljcc/analyzer.clj
+++ b/src/cljcc/analyzer.clj
@@ -1,12 +1,80 @@
 (ns cljcc.analyzer
   (:require [cljcc.lexer :as l]
+            [clojure.pprint :as pp]
+            [cljcc.util :as u]
             [cljcc.parser :as p]))
 
-()
+(defn- unique-identifier
+  ([] (unique-identifier "analyzer"))
+  ([identifier] (u/create-identifier! identifier)))
 
-(defn validate [ast])
+(defn- resolve-exp [e mp]
+  (condp = (:exp-type e)
+    :constant-exp e
+    :variable-exp (if (contains? mp (:identifier e))
+                    (p/variable-exp-node (get mp (:identifier e)))
+                    (throw (ex-info "Undeclared variable seen." {:variable e})))
+    :assignment-exp (let [left (:left e)
+                          right (:right e)
+                          left-var? (= :variable-exp (:exp-type left))]
+                      (if left-var?
+                        (p/assignment-exp-node (resolve-exp left mp)
+                                               (resolve-exp right mp))
+                        (throw (ex-info "Invalid lvalue." {:lvalue e}))))
+    :binary-exp (p/binary-exp-node (resolve-exp (:left e) mp)
+                                   (resolve-exp (:right e) mp)
+                                   (:binary-operator e))
+    :unary-exp (p/unary-exp-node (:unary-operator e) (resolve-exp (:value e) mp))
+    (throw (ex-info "Analyzer error. Invalid expression type" {:exp e}))))
+
+(defn- resolve-declaration [d mp]
+  (if (contains? mp (:identifier d))
+    (throw (ex-info "Analyzer error. Duplicate variable declaration." {:declaration d}))
+    (let [ident (:identifier d)
+          unique-name (unique-identifier ident)
+          updated-mp (assoc mp ident unique-name)
+          _ (pp/pprint mp)
+          _ (pp/pprint updated-mp)
+          init (when (:initial d) (resolve-exp (:initial d) updated-mp))]
+      (if init
+        {:declaration (p/declaration-node unique-name init)
+         :variable-map updated-mp}
+        {:declaration (p/declaration-node unique-name)
+         :variable-map updated-mp}))))
+
+(defn- resolve-statement [s mp]
+  (condp = (:statement-type s)
+    :return (p/return-statement-node (resolve-exp (:value s) mp))
+    :expression (p/expression-statement-node (resolve-exp (:value s) mp))
+    :empty (p/empty-statement-node)
+    (throw (ex-info "Analyzer error. Invalid statement." {:statement s}))))
+
+(defn- resolve-block-item [item mp]
+  (let [type (:type item)]
+    (cond
+      (= type :declaration) (let [v (resolve-declaration item mp)]
+                              {:item (:declaration v)
+                               :variable-map (:variable-map v)})
+      (= type :statement) {:item (resolve-statement item mp)
+                           :variable-map mp}
+      :else (throw (ex-info "Analyzer Error. Invalid statement/declaration." {item item})))))
+
+(defn- validate-function [f]
+  (let [updated-body (reduce
+                      (fn [acc item]
+                        (let [v (resolve-block-item item (:variable-map acc))]
+                          {:body (conj (:body acc) (:item v))
+                           :variable-map (:variable-map v)}))
+                      {:body []
+                       :variable-map {}}
+                      (:body f))]
+    (assoc f :body updated-body)))
+
+(defn validate [ast]
+  (map validate-function ast))
 
 (defn- validate-from-src [s]
+  (u/reset-counter!)
   (-> s
       l/lex
       p/parse
@@ -14,4 +82,22 @@
 
 (comment
 
+  (pp/pprint
+   (validate-from-src
+    "int main (void) {
+;
+return 0;
+}"))
+
+  (pp/pprint
+   (p/parse-from-src
+    "int main (void) {
+int x;
+int a = -1;
+int b = 2;
+
+int c = b = 4 + 4;
+return 12 / 12321312 + 12312 % 4;
+}"))
+
   ())
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