first commit

stringify.cpp

@@ -0,0 +1,101 @@
+#include <string>
+#include <sstream>
+#include <cstring>
+#include <algorithm>
+#include "expr.hpp"
+
+struct StringifyVisitor : Visitor {
+
+    char    *dst;
+    uint32_t num;
+    uint32_t max;
+
+    void append(const char *str, uint32_t len)
+    {
+        if (num < max) {
+            uint32_t cpy = std::min(len, max - num);
+            memcpy(dst + num, str, cpy);
+        }
+        num += len;
+    }
+
+    StringifyVisitor(char *dst_, uint32_t max_)
+    {
+        dst = dst_;
+        max = max_;
+        num = 0;
+    }
+
+    void visit_int(IntValue *node)
+    {
+        std::ostringstream sstr;
+        sstr << node->val;
+        std::string str = sstr.str();
+        append(str.c_str(), str.size());
+    }
+
+    void visit_float(FloatValue *node)
+    {
+        std::ostringstream sstr;
+        sstr << node->val;
+        std::string str = sstr.str();
+        append(str.c_str(), str.size());
+    }
+
+    void visit_neg(NegOperation *node)
+    {
+        append("-", 1);
+        node->op->visit(*this);
+    }
+
+    void visit_add(AddOperation *node)
+    {
+        append("(", 1);
+        node->lhs->visit(*this);
+        append(" + ", 3);
+        node->rhs->visit(*this);
+        append(")", 1);
+    }
+
+    void visit_sub(SubOperation *node)
+    {
+        append("(", 1);
+        node->lhs->visit(*this);
+        append(" - ", 3);
+        node->rhs->visit(*this);
+        append(")", 1);
+    }
+
+    void visit_mul(MulOperation *node)
+    {
+        append("(", 1);
+        node->lhs->visit(*this);
+        append(" * ", 3);
+        node->rhs->visit(*this);
+        append(")", 1);
+    }
+
+    void visit_div(DivOperation *node)
+    {
+        append("(", 1);
+        node->lhs->visit(*this);
+        append(" / ", 3);
+        node->rhs->visit(*this);
+        append(")", 1);
+    }
+};
+
+uint32_t stringify(Expr *e, char *dst, uint32_t max)
+{
+    StringifyVisitor visitor(dst, max);
+    e->visit(visitor);
+    uint32_t num = visitor.num;
+
+    if (max > 0) {
+        if (num == max)
+            num--;
+        dst[num] = '\0';
+    }
+
+    return num;
+}