abstract-parser: skip leading spaces in the input

... when detecting the input data format.  None of the supported formats
treats leading spaces as significant.

Author: kdudka

src/abstract-parser.cc

@@ -26,8 +26,8 @@
 
 AbstractParser* createParser(InStream &input)
 {
-    // sniff the first two chars from the input
-    InStreamLookAhead head(input, 2U);
+    // skip all white-spaces and sniff the first two chars from the input
+    InStreamLookAhead head(input, 2U, /* skipWhiteSpaces */ true);
 
     switch (head[0]) {
         case '{':

src/instream.cc

@@ -62,13 +62,25 @@ void InStream::handleError(const std::string msg, const long line)
     std::cerr << ": error: " << msg << "\n";
 }
 
-InStreamLookAhead::InStreamLookAhead(InStream &input, const unsigned size)
+InStreamLookAhead::InStreamLookAhead(
+        InStream               &input,
+        const unsigned          size,
+        bool                    skipWhiteSpaces)
 {
     std::istream &inStr = input.str();
 
     // read `size` chars from input
-    while (buf_.size() < size)
-        buf_.push_back(inStr.get());
+    while (buf_.size() < size) {
+        const int c = inStr.get();
+        if (skipWhiteSpaces && isspace(c) && !!inStr)
+            // skip a white-space
+            continue;
+
+        // only the leading white-spaces are skipped
+        skipWhiteSpaces = false;
+
+        buf_.push_back(c);
+    }
 
     // put the chars back to the input stream
     for (auto it = buf_.rbegin(); it != buf_.rend(); ++it)

src/instream.hh

@@ -59,7 +59,10 @@ class InStream {
 
 class InStreamLookAhead {
     public:
-        InStreamLookAhead(InStream &, unsigned size);
+        InStreamLookAhead(
+                InStream       &inStr,
+                unsigned        size,
+                bool            skipWhiteSpaces = false);
 
         char operator[](const unsigned idx) const {
             return buf_.at(idx);

tests/csgrep/74-coverity-leading-space-args.txt

@@ -117,3 +117,4 @@ test_csgrep("70-csparser-included-from-note"          )
 test_csgrep("71-csgrep-drop-scan-props"               )
 test_csgrep("72-abstract-parser-gcc-builtin"          )
 test_csgrep("73-coverity-misra-checkers"              )
+test_csgrep("74-coverity-leading-space"               )