Add new writeJSON methods

Create an alternative to getJSON to allow an object handle to be written as JSON without the overhead of creating a JSON object.

include/qpdf/QPDFObjectHandle.hh

@@ -1353,6 +1353,8 @@ class QPDFObjectHandle
         return obj.get();
     }
 
+    void writeJSON(int json_version, JSON::Writer& p, bool dereference_indirect = false);
+
   private:
     QPDF_Array* asArray();
     QPDF_Bool* asBool();

libqpdf/QPDFObjectHandle.cc

@@ -3,6 +3,7 @@
 #include <qpdf/BufferInputSource.hh>
 #include <qpdf/Pl_Buffer.hh>
 #include <qpdf/Pl_QPDFTokenizer.hh>
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/QPDF.hh>
 #include <qpdf/QPDFExc.hh>
 #include <qpdf/QPDFLogger.hh>
@@ -1621,6 +1622,18 @@ QPDFObjectHandle::getJSON(int json_version, bool dereference_indirect)
     }
 }
 
+void
+QPDFObjectHandle::writeJSON(int json_version, JSON::Writer& p, bool dereference_indirect)
+{
+    if (!dereference_indirect && isIndirect()) {
+        p << "\"" << getObjGen().unparse(' ') << " R\"";
+    } else if (!dereference()) {
+        throw std::logic_error("attempted to dereference an uninitialized QPDFObjectHandle");
+    } else {
+        obj->writeJSON(json_version, p);
+    }
+}
+
 JSON
 QPDFObjectHandle::getStreamJSON(
     int json_version,

libqpdf/QPDF_Array.cc

@@ -1,5 +1,6 @@
 #include <qpdf/QPDF_Array.hh>
 
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/QPDFObjectHandle.hh>
 #include <qpdf/QPDFObject_private.hh>
 #include <qpdf/QTC.hh>
@@ -180,6 +181,43 @@ QPDF_Array::getJSON(int json_version)
     return j_array;
 }
 
+void
+QPDF_Array::writeJSON(int json_version, JSON::Writer& p)
+{
+    p.writeStart('[');
+    if (sp) {
+        int next = 0;
+        for (auto& item: sp->elements) {
+            int key = item.first;
+            for (int j = next; j < key; ++j) {
+                p.writeNext() << "null";
+            }
+            p.writeNext();
+            auto og = item.second->getObjGen();
+            if (og.isIndirect()) {
+                p << "\"" << og.unparse(' ') << " R\"";
+            } else {
+                item.second->writeJSON(json_version, p);
+            }
+            next = ++key;
+        }
+        for (int j = next; j < sp->size; ++j) {
+            p.writeNext() << "null";
+        }
+    } else {
+        for (auto const& item: elements) {
+            p.writeNext();
+            auto og = item->getObjGen();
+            if (og.isIndirect()) {
+                p << "\"" << og.unparse(' ') << " R\"";
+            } else {
+                item->writeJSON(json_version, p);
+            }
+        }
+    }
+    p.writeEnd(']');
+}
+
 QPDFObjectHandle
 QPDF_Array::at(int n) const noexcept
 {

libqpdf/QPDF_Bool.cc

@@ -1,5 +1,7 @@
 #include <qpdf/QPDF_Bool.hh>
 
+#include <qpdf/JSON_writer.hh>
+
 QPDF_Bool::QPDF_Bool(bool val) :
     QPDFValue(::ot_boolean, "boolean"),
     val(val)
@@ -30,6 +32,12 @@ QPDF_Bool::getJSON(int json_version)
     return JSON::makeBool(this->val);
 }
 
+void
+QPDF_Bool::writeJSON(int json_version, JSON::Writer& p)
+{
+    p << val;
+}
+
 bool
 QPDF_Bool::getVal() const
 {

libqpdf/QPDF_Destroyed.cc

@@ -34,3 +34,9 @@ QPDF_Destroyed::getJSON(int json_version)
     throw std::logic_error("attempted to get JSON from a QPDFObjectHandle from a destroyed QPDF");
     return JSON::makeNull();
 }
+
+void
+QPDF_Destroyed::writeJSON(int json_version, JSON::Writer& p)
+{
+    throw std::logic_error("attempted to get JSON from a QPDFObjectHandle from a destroyed QPDF");
+}

libqpdf/QPDF_Dictionary.cc

@@ -1,5 +1,6 @@
 #include <qpdf/QPDF_Dictionary.hh>
 
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/QPDFObject_private.hh>
 #include <qpdf/QPDF_Name.hh>
 #include <qpdf/QPDF_Null.hh>
@@ -91,6 +92,33 @@ QPDF_Dictionary::getJSON(int json_version)
     return j;
 }
 
+void
+QPDF_Dictionary::writeJSON(int json_version, JSON::Writer& p)
+{
+    p.writeStart('{');
+    for (auto& iter: this->items) {
+        if (!iter.second.isNull()) {
+            p.writeNext();
+            if (json_version == 1) {
+                p << "\"" << JSON::Writer::encode_string(QPDF_Name::normalizeName(iter.first)) << "\": ";
+            } else {
+                bool has_8bit_chars;
+                bool is_valid_utf8;
+                bool is_utf16;
+                QUtil::analyze_encoding(iter.first, has_8bit_chars, is_valid_utf8, is_utf16);
+                if (!has_8bit_chars || is_valid_utf8) {
+                    p << "\"" << JSON::Writer::encode_string(iter.first) << "\": ";
+                } else {
+                    p << "\"n:" << JSON::Writer::encode_string(QPDF_Name::normalizeName(iter.first))
+                      << "\": ";
+                }
+            }
+            iter.second.writeJSON(json_version, p);
+        }
+    }
+    p.writeEnd('}');
+}
+
 bool
 QPDF_Dictionary::hasKey(std::string const& key)
 {

libqpdf/QPDF_InlineImage.cc

@@ -1,5 +1,7 @@
 #include <qpdf/QPDF_InlineImage.hh>
 
+#include <qpdf/JSON_writer.hh>
+
 QPDF_InlineImage::QPDF_InlineImage(std::string const& val) :
     QPDFValue(::ot_inlineimage, "inline-image"),
     val(val)
@@ -29,3 +31,9 @@ QPDF_InlineImage::getJSON(int json_version)
 {
     return JSON::makeNull();
 }
+
+void
+QPDF_InlineImage::writeJSON(int json_version, JSON::Writer& p)
+{
+    p << "null";
+}

libqpdf/QPDF_Integer.cc

@@ -1,5 +1,6 @@
 #include <qpdf/QPDF_Integer.hh>
 
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/QUtil.hh>
 
 QPDF_Integer::QPDF_Integer(long long val) :
@@ -32,6 +33,12 @@ QPDF_Integer::getJSON(int json_version)
     return JSON::makeInt(this->val);
 }
 
+void
+QPDF_Integer::writeJSON(int json_version, JSON::Writer& p)
+{
+    p << std::to_string(this->val);
+}
+
 long long
 QPDF_Integer::getVal() const
 {

libqpdf/QPDF_Name.cc

@@ -1,5 +1,6 @@
 #include <qpdf/QPDF_Name.hh>
 
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/QUtil.hh>
 
 QPDF_Name::QPDF_Name(std::string const& name) :
@@ -68,3 +69,21 @@ QPDF_Name::getJSON(int json_version)
         }
     }
 }
+
+void
+QPDF_Name::writeJSON(int json_version, JSON::Writer& p)
+{
+    if (json_version == 1) {
+        p << "\"" << JSON::Writer::encode_string(normalizeName(name)) << "\"";
+    } else {
+        bool has_8bit_chars;
+        bool is_valid_utf8;
+        bool is_utf16;
+        QUtil::analyze_encoding(this->name, has_8bit_chars, is_valid_utf8, is_utf16);
+        if (!has_8bit_chars || is_valid_utf8) {
+            p << "\"" << JSON::Writer::encode_string(name) << "\"";
+        } else {
+            p << "\"n:" << JSON::Writer::encode_string(normalizeName(name)) << "\"";
+        }
+    }
+}

libqpdf/QPDF_Null.cc

@@ -1,5 +1,6 @@
 #include <qpdf/QPDF_Null.hh>
 
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/QPDFObject_private.hh>
 
 QPDF_Null::QPDF_Null() :
@@ -49,3 +50,9 @@ QPDF_Null::getJSON(int json_version)
     // If this is updated, QPDF_Array::getJSON must also be updated.
     return JSON::makeNull();
 }
+
+void
+QPDF_Null::writeJSON(int json_version, JSON::Writer& p)
+{
+    p << "null";
+}

libqpdf/QPDF_Operator.cc

@@ -1,5 +1,7 @@
 #include <qpdf/QPDF_Operator.hh>
 
+#include <qpdf/JSON_writer.hh>
+
 QPDF_Operator::QPDF_Operator(std::string const& val) :
     QPDFValue(::ot_operator, "operator"),
     val(val)
@@ -29,3 +31,9 @@ QPDF_Operator::getJSON(int json_version)
 {
     return JSON::makeNull();
 }
+
+void
+QPDF_Operator::writeJSON(int json_version, JSON::Writer& p)
+{
+    p << "null";
+}

libqpdf/QPDF_Real.cc

@@ -1,5 +1,6 @@
 #include <qpdf/QPDF_Real.hh>
 
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/QUtil.hh>
 
 QPDF_Real::QPDF_Real(std::string const& val) :
@@ -56,3 +57,18 @@ QPDF_Real::getJSON(int json_version)
     }
     return JSON::makeNumber(result);
 }
+
+void
+QPDF_Real::writeJSON(int json_version, JSON::Writer& p)
+{
+    if (this->val.length() == 0) {
+        // Can't really happen...
+        p << "0";
+    } else if (this->val.at(0) == '.') {
+        p << "0" << this->val;
+    } else if (this->val.length() >= 2 && this->val.at(0) == '-' && this->val.at(1) == '.') {
+        p << "-0." << this->val.substr(2);
+    } else {
+        p << this->val;
+    }
+}

libqpdf/QPDF_Reserved.cc

@@ -32,3 +32,9 @@ QPDF_Reserved::getJSON(int json_version)
     throw std::logic_error("QPDFObjectHandle: attempting to get JSON from a reserved object");
     return JSON::makeNull();
 }
+
+void
+QPDF_Reserved::writeJSON(int json_version, JSON::Writer& p)
+{
+    throw std::logic_error("QPDFObjectHandle: attempting to get JSON from a reserved object");
+}

libqpdf/QPDF_Stream.cc

@@ -1,6 +1,7 @@
 #include <qpdf/QPDF_Stream.hh>
 
 #include <qpdf/ContentNormalizer.hh>
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/Pipeline.hh>
 #include <qpdf/Pl_Base64.hh>
 #include <qpdf/Pl_Buffer.hh>
@@ -185,6 +186,12 @@ QPDF_Stream::getJSON(int json_version)
     return getStreamJSON(json_version, qpdf_sj_none, qpdf_dl_none, nullptr, "");
 }
 
+void
+QPDF_Stream::writeJSON(int json_version, JSON::Writer& p)
+{
+    stream_dict.writeJSON(json_version, p);
+}
+
 JSON
 QPDF_Stream::getStreamJSON(
     int json_version,

libqpdf/QPDF_String.cc

@@ -1,5 +1,6 @@
 #include <qpdf/QPDF_String.hh>
 
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/QUtil.hh>
 
 // DO NOT USE ctype -- it is locale dependent for some things, and it's not worth the risk of
@@ -74,6 +75,30 @@ QPDF_String::getJSON(int json_version)
     return JSON::makeString(result);
 }
 
+void
+QPDF_String::writeJSON(int json_version, JSON::Writer& p)
+{
+    auto candidate = getUTF8Val();
+    if (json_version == 1) {
+
+        p << "\"" << JSON::Writer::encode_string(candidate) << "\"";
+    } else {
+        // See if we can unambiguously represent as Unicode.
+        if (QUtil::is_utf16(this->val) || QUtil::is_explicit_utf8(this->val)) {
+            p << "\"u:" << JSON::Writer::encode_string(candidate) <<"\"";
+            return;
+        } else if (!useHexString()) {
+            std::string test;
+            if (QUtil::utf8_to_pdf_doc(candidate, test, '?') && (test == this->val)) {
+                // This is a PDF-doc string that can be losslessly encoded as Unicode.
+                p << "\"u:" << JSON::Writer::encode_string(candidate) <<"\"";
+                return;
+            }
+        }
+        p << "\"b:" << QUtil::hex_encode(val) <<"\"";
+    }
+}
+
 bool
 QPDF_String::useHexString() const
 {

libqpdf/QPDF_Unresolved.cc

@@ -33,3 +33,9 @@ QPDF_Unresolved::getJSON(int json_version)
     throw std::logic_error("attempted to get JSON from an unresolved QPDFObjectHandle");
     return JSON::makeNull();
 }
+
+void
+QPDF_Unresolved::writeJSON(int json_version, JSON::Writer& p)
+{
+    throw std::logic_error("attempted to get JSON from an unresolved QPDFObjectHandle");
+}

libqpdf/QPDF_json.cc

@@ -1,6 +1,7 @@
 #include <qpdf/QPDF.hh>
 
 #include <qpdf/FileInputSource.hh>
+#include <qpdf/JSON_writer.hh>
 #include <qpdf/Pl_Base64.hh>
 #include <qpdf/Pl_StdioFile.hh>
 #include <qpdf/QIntC.hh>
@@ -864,9 +865,15 @@ void
 QPDF::writeJSONObject(
     int version, Pipeline* p, bool& first, std::string const& key, QPDFObjectHandle& obj)
 {
-    auto j = JSON::makeDictionary();
-    j.addDictionaryMember("value", obj.getJSON(version, true));
-    JSON::writeDictionaryItem(p, first, key, j, 3);
+    if (first) {
+        *p << "\n      \"" << key << "\": {\n        \"value\": ";
+        first = false;
+    } else {
+        *p << ",\n      \"" << key << "\": {\n        \"value\": ";
+    }
+    auto w = JSON::Writer(p, 4);
+    obj.writeJSON(version, w, true);
+    *p << "\n      }";
 }
 
 void