cprintf: support a configurable width and precision ("*" in printf)

src/base/cprintf.cc

@@ -40,7 +40,7 @@ using namespace std;
 namespace cp {
 
 Print::Print(std::ostream &stream, const std::string &format)
-    : stream(stream), format(format.c_str()), ptr(format.c_str())
+    : stream(stream), format(format.c_str()), ptr(format.c_str()), cont(false)
 {
     saved_flags = stream.flags();
     saved_fill = stream.fill();
@@ -48,7 +48,7 @@ Print::Print(std::ostream &stream, const std::string &format)
 }
 
 Print::Print(std::ostream &stream, const char *format)
-    : stream(stream), format(format), ptr(format)
+    : stream(stream), format(format), ptr(format), cont(false)
 {
     saved_flags = stream.flags();
     saved_fill = stream.fill();
@@ -60,8 +60,10 @@ Print::~Print()
 }
 
 void
-Print::process(Format &fmt)
+Print::process()
 {
+    fmt.clear();
+
     size_t len;
 
     while (*ptr) {
@@ -221,8 +223,15 @@ Print::process(Format &fmt)
             number = number * 10 + (*ptr - '0');
             break;
 
+          case '*':
+            if (have_precision)
+                fmt.get_precision = true;
+            else
+                fmt.get_width = true;
+            break;
+
           case '%':
-            assert("we shouldn't get here");
+            assert(false && "we shouldn't get here");
             break;
 
           default:

src/base/cprintf.hh

@@ -51,24 +51,53 @@ struct Print
     std::ostream &stream;
     const char *format;
     const char *ptr;
+    bool cont;
 
     std::ios::fmtflags saved_flags;
     char saved_fill;
     int saved_precision;
 
-    void process(Format &fmt);
+    Format fmt;
+    void process();
 
   public:
     Print(std::ostream &stream, const std::string &format);
     Print(std::ostream &stream, const char *format);
     ~Print();
 
+    int
+    get_number(int data)
+    {
+        return data;
+    }
+    
+    template <typename T>
+    int
+    get_number(const T& data)
+    {
+        return 0;
+    }
+
     template <typename T>
     void
     add_arg(const T &data)
     {
-        Format fmt;
-        process(fmt);
+        if (!cont)
+            process();
+
+        if (fmt.get_width) {
+            fmt.get_width = false;
+            cont = true;
+            fmt.width = get_number(data);
+            return;
+        }
+            
+        if (fmt.get_precision) {
+            fmt.get_precision = false;
+            cont = true;
+            fmt.precision = get_number(data);
+            return;
+        }
 
         switch (fmt.format) {
           case Format::character:

src/base/cprintf_formats.hh

@@ -50,6 +50,8 @@ struct Format
     enum { best, fixed, scientific } float_format;
     int precision;
     int width;
+    bool get_precision;
+    bool get_width;
 
     Format() { clear(); }
 
@@ -65,6 +67,8 @@ struct Format
         format = none;
         precision = -1;
         width = 0;
+        get_precision = false;
+        get_width = false;
     }
 };
 

src/unittest/cprintftest.cc

@@ -167,6 +167,13 @@ main()
 
     cprintf("%c  %c\n", 'c', 65);
 
-    cout << '9';
+    cout << '9' << endl;
+
+    cout << endl;
+
+    cprintf("%08.4f\n", 99.99);
+    cprintf("%0*.*f\n", 8, 4, 99.99);
+    cprintf("%07.*f\n", 4, 1.234);
+    cprintf("%#0*x\n", 9, 123412);
     return 0;
 }