From 5497e8ed67dcf781818f16176c2e6780d34ba3b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Sun, 21 Jun 2020 20:05:26 +0200
Subject: [PATCH] ExprEngine; Improved handling of stream read

---
 lib/exprengine.cpp      | 23 +++++++++++++++++++++++
 test/testexprengine.cpp | 16 ++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/lib/exprengine.cpp b/lib/exprengine.cpp
index 0cfdb45ef..a25720b4d 100644
--- a/lib/exprengine.cpp
+++ b/lib/exprengine.cpp
@@ -1936,6 +1936,26 @@ static ExprEngine::ValuePtr executeDot(const Token *tok, Data &data)
     return memberValue;
 }
 
+static void streamReadSetValue(const Token *tok, Data &data)
+{
+    if (!tok || !tok->valueType())
+        return;
+    auto rangeValue = getValueRangeFromValueType(data.getNewSymbolName(), tok->valueType(), *data.settings);
+    if (rangeValue)
+        assignExprValue(tok, rangeValue, data);
+}
+
+static ExprEngine::ValuePtr executeStreamRead(const Token *tok, Data &data)
+{
+    tok = tok->astOperand2();
+    while (Token::simpleMatch(tok, ">>")) {
+        streamReadSetValue(tok->astOperand1(), data);
+        tok = tok->astOperand2();
+    }
+    streamReadSetValue(tok, data);
+    return ExprEngine::ValuePtr();
+}
+
 static ExprEngine::ValuePtr executeBinaryOp(const Token *tok, Data &data)
 {
     ExprEngine::ValuePtr v1 = executeExpression(tok->astOperand1(), data);
@@ -2085,6 +2105,9 @@ static ExprEngine::ValuePtr executeExpression1(const Token *tok, Data &data)
         return std::make_shared<ExprEngine::IntRange>(std::to_string(v), v, v);
     }
 
+    if (data.tokenizer->isCPP() && tok->str() == ">>" && !tok->astParent() && tok->isBinaryOp() && Token::Match(tok->astOperand1(), "%name%|::"))
+        return executeStreamRead(tok, data);
+
     if (tok->astOperand1() && tok->astOperand2())
         return executeBinaryOp(tok, data);
 
diff --git a/test/testexprengine.cpp b/test/testexprengine.cpp
index 28cf10f76..c01455cd8 100644
--- a/test/testexprengine.cpp
+++ b/test/testexprengine.cpp
@@ -60,6 +60,8 @@ private:
         TEST_CASE(if5);
         TEST_CASE(ifelse1);
 
+        TEST_CASE(istream);
+
         TEST_CASE(switch1);
         TEST_CASE(switch2);
 
@@ -407,6 +409,20 @@ private:
     }
 
 
+    void istream() {
+        const char code[] = "void foo(const std::string& in) {\n"
+                            "    std::istringstream istr(in);\n"
+                            "    unsigned short x=5;\n"
+                            "    istr >> x;\n"
+                            "    x==3;\n"
+                            "}";
+
+        ASSERT_EQUALS("(and (>= $2 0) (<= $2 65535))\n"
+                      "(= $2 3)\n"
+                      "z3::sat\n",
+                      expr(code, "=="));
+    }
+
     void switch1() {
         const char code[] = "void f(int x) {\n"
                             "    switch (x) {\n"