DDXParserSAX2.cc

// -*- mode: c++; c-basic-offset:4 -*-

// This file is part of libdap, A C++ implementation of the OPeNDAP Data
// Access Protocol.

// Copyright (c) 2003 OPeNDAP, Inc.
// Author: James Gallagher <jgallagher@opendap.org>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
// You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.

#include "config.h"

//#define DODS_DEBUG 1
//#define DODS_DEBUG2 1

#include <cstring>
#include <cstdarg>

#include "BaseType.h"
#include "Byte.h"
#include "Int16.h"
#include "UInt16.h"
#include "Int32.h"
#include "UInt32.h"
#include "Float32.h"
#include "Float64.h"
#include "Str.h"
#include "Url.h"
#include "Array.h"
#include "Structure.h"
#include "Sequence.h"
#include "Grid.h"

#include "DDXParserSAX2.h"

#include "util.h"
#include "mime_util.h"
#include "debug.h"

namespace libdap {

#if defined(DODS_DEBUG) || defined(DODS_DEUG2)
static const char *states[] =
    {
        "start",

        "dataset",

        "attribute_container",
        "attribute",
        "attribute_value",
        "other_xml_attribute",

        "alias",

        "simple_type",

        "array",
        "dimension",

        "grid",
        "map",

        "structure",
        "sequence",

        "blob href",

        "unknown",
        "error"
    };
#endif
// Glue the BaseTypeFactory to the enum-based factory defined statically
// here.

BaseType *DDXParser::factory(Type t, const string & name)
{
    switch (t) {
    case dods_byte_c:
        return d_factory->NewByte(name);

    case dods_int16_c:
        return d_factory->NewInt16(name);

    case dods_uint16_c:
        return d_factory->NewUInt16(name);

    case dods_int32_c:
        return d_factory->NewInt32(name);

    case dods_uint32_c:
        return d_factory->NewUInt32(name);

    case dods_float32_c:
        return d_factory->NewFloat32(name);

    case dods_float64_c:
        return d_factory->NewFloat64(name);

    case dods_str_c:
        return d_factory->NewStr(name);

    case dods_url_c:
        return d_factory->NewUrl(name);

    case dods_array_c:
        return d_factory->NewArray(name);

    case dods_structure_c:
        return d_factory->NewStructure(name);

    case dods_sequence_c:
        return d_factory->NewSequence(name);

    case dods_grid_c:
        return d_factory->NewGrid(name);

    default:
        return 0;
    }
}

static bool is_not(const char *name, const char *tag)
{
    return strcmp(name, tag) != 0;
}

void DDXParser::set_state(DDXParser::ParseState state)
{
    s.push(state);
}

DDXParser::ParseState DDXParser::get_state() const
{
    return s.top();
}

void DDXParser::pop_state()
{
    s.pop();
}

void DDXParser::transfer_xml_attrs(const xmlChar **attributes, int nb_attributes)
{
    if (!attribute_table.empty())
        attribute_table.clear(); // erase old attributes

    unsigned int index = 0;
    for (int i = 0; i < nb_attributes; ++i, index += 5) {
        // Make a value using the attribute name and the prefix, namespace URI
        // and the value. The prefix might be null.
        attribute_table.insert(map<string, XMLAttribute>::value_type(
                string((const char *)attributes[index]),
                XMLAttribute(attributes + index + 1)));

        DBG(cerr << "Attribute '" << (const char *)attributes[index] << "': "
                << attribute_table[(const char *)attributes[index]].value << endl);
    }
}

void DDXParser::transfer_xml_ns(const xmlChar **namespaces, int nb_namespaces)
{
    for (int i = 0; i < nb_namespaces; ++i ) {
        // make a value with the prefix and namespace URI. The prefix might be
        // null.
        namespace_table.insert(map<string,string>::value_type(
                namespaces[i*2] != 0 ? (const char *)namespaces[i*2] : "",
                (const char *)namespaces[i*2+1]));
    }
}

bool DDXParser::check_required_attribute(const string & attr)
{
    map < string, XMLAttribute >::iterator i = attribute_table.find(attr);
    if (i == attribute_table.end())
        ddx_fatal_error(this, "Required attribute '%s' not found.",
                        attr.c_str());
    return true;
}

bool DDXParser::check_attribute(const string & attr)
{
    return (attribute_table.find(attr) != attribute_table.end());
}

void DDXParser::process_attribute_element(const xmlChar **attrs, int nb_attributes)
{
    // These methods set the state to parser_error if a problem is found.
    transfer_xml_attrs(attrs, nb_attributes);

    bool error = !(check_required_attribute(string("name"))
                   && check_required_attribute(string("type")));
    if (error)
        return;

    if (attribute_table["type"].value == "Container") {
        set_state(inside_attribute_container);

        AttrTable *child;
        AttrTable *parent = at_stack.top();

        child = parent->append_container(attribute_table["name"].value);
        at_stack.push(child);   // save.
        DBG2(cerr << "Pushing at" << endl);
    }
    else if (attribute_table["type"].value == "OtherXML") {
        set_state(inside_other_xml_attribute);

        dods_attr_name = attribute_table["name"].value;
        dods_attr_type = attribute_table["type"].value;
    }
    else {
        set_state(inside_attribute);
        // *** Modify parser. Add a special state for inside OtherXML since it
        // does not use the <value> element.

        dods_attr_name = attribute_table["name"].value;
        dods_attr_type = attribute_table["type"].value;
    }
}

void DDXParser::process_attribute_alias(const xmlChar **attrs, int nb_attributes)
{
    transfer_xml_attrs(attrs, nb_attributes);
    if (check_required_attribute(string("name"))
        && check_required_attribute(string("attribute"))) {
        set_state(inside_alias);
        at_stack.top()->attr_alias(attribute_table["name"].value,
                                   attribute_table["attribute"].value);
    }
}

void DDXParser::process_variable(Type t, ParseState s, const xmlChar **attrs,
        int nb_attributes)
{
    transfer_xml_attrs(attrs, nb_attributes);

    set_state(s);

    if (bt_stack.top()->type() == dods_array_c
            || check_required_attribute("name")) { // throws on error/false
        BaseType *btp = factory(t, attribute_table["name"].value);
        if (!btp) {
            ddx_fatal_error(this, "Internal parser error; could not instantiate the variable '%s'.",
                attribute_table["name"].value.c_str());
        }
        else {
            // Only run this code if btp is not null! jhrg 9/14/15
            // Once we make the new variable, we not only load it on to the
            // BaseType stack, we also load its AttrTable on the AttrTable stack.
            // The attribute processing software always operates on the AttrTable
            // at the top of the AttrTable stack (at_stack).
            bt_stack.push(btp);
            at_stack.push(&btp->get_attr_table());
        }
    }
}

void DDXParser::process_dimension(const xmlChar **attrs, int nb_attributes)
{
    transfer_xml_attrs(attrs, nb_attributes);
    if (check_required_attribute(string("size"))) {
        set_state(inside_dimension);
        Array *ap = dynamic_cast < Array * >(bt_stack.top());
        if (!ap) {
            ddx_fatal_error(this, "Parse error: Expected an array variable.");
            return;
        }
        
        ap->append_dim(atoi(attribute_table["size"].value.c_str()),
                       attribute_table["name"].value);
    }
}

void DDXParser::process_blob(const xmlChar **attrs, int nb_attributes)
{
    transfer_xml_attrs(attrs, nb_attributes);
    if (check_required_attribute(string("href"))) {
        set_state(inside_blob_href);
        *blob_href = attribute_table["href"].value;
    }
}

inline bool
DDXParser::is_attribute_or_alias(const char *name, const xmlChar **attrs,
        int nb_attributes)
{
    if (strcmp(name, "Attribute") == 0) {
        process_attribute_element(attrs, nb_attributes);
        // next state: inside_attribtue or inside_attribute_container
        return true;
    }
    else if (strcmp(name, "Alias") == 0) {
        process_attribute_alias(attrs, nb_attributes);
        // next state: inside_alias
        return true;
    }

    return false;
}

inline bool DDXParser::is_variable(const char *name, const xmlChar **attrs,
        int nb_attributes)
{
    Type t = get_type(name);
    //if ((t = is_simple_type(name)) != dods_null_c) {
    if (is_simple_type(t)) {
        process_variable(t, inside_simple_type, attrs, nb_attributes);
        return true;
    }
    else if (strcmp(name, "Array") == 0) {
        process_variable(dods_array_c, inside_array, attrs, nb_attributes);
        return true;
    }
    else if (strcmp(name, "Structure") == 0) {
        process_variable(dods_structure_c, inside_structure, attrs, nb_attributes);
        return true;
    }
    else if (strcmp(name, "Sequence") == 0) {
        process_variable(dods_sequence_c, inside_sequence, attrs, nb_attributes);
        return true;
    }
    else if (strcmp(name, "Grid") == 0) {
        process_variable(dods_grid_c, inside_grid, attrs, nb_attributes);
        return true;
    }

    return false;
}

void DDXParser::finish_variable(const char *tag, Type t, const char *expected)
{
    if (strcmp(tag, expected) != 0) {
        DDXParser::ddx_fatal_error(this,
                                   "Expected an end tag for a %s; found '%s' instead.",
                                   expected, tag);
        return;
    }

    pop_state();

    BaseType *btp = bt_stack.top();

    bt_stack.pop();
    at_stack.pop();

    if (btp->type() != t) {
        DDXParser::ddx_fatal_error(this,
                                   "Internal error: Expected a %s variable.",
                                   expected);
        delete btp;
        return;
    }
    // Once libxml2 validates, this can go away. 05/30/03 jhrg
    if (t == dods_array_c
        && static_cast<Array*>(btp)->dimensions() == 0) {
        DDXParser::ddx_fatal_error(this,
                                   "No dimension element included in the Array '%s'.",
                                   btp->name().c_str());
        delete btp;
        return;
    }

    BaseType *parent = bt_stack.top();

    if (!(parent->is_vector_type() || parent->is_constructor_type())) {
        DDXParser::ddx_fatal_error(this,
                                   "Tried to add the array variable '%s' to a non-constructor type (%s %s).",
                                   tag,
                                   bt_stack.top()->type_name().c_str(),
                                   bt_stack.top()->name().c_str());
        delete btp;
        return;
    }

    parent->add_var_nocopy(btp);
}


void DDXParser::ddx_start_document(void * p)
{
    DDXParser *parser = static_cast<DDXParser*>(p);
    parser->error_msg = "";
    parser->char_data = "";

    // init attr table stack.
    parser->at_stack.push(&parser->dds->get_attr_table());

    // Trick; DDS *should* be a child of Structure. To simplify parsing,
    // stuff a Structure on the bt_stack and dump the top level variables
    // there. Once we're done, transfer the variables to the DDS.
    parser->bt_stack.push(new Structure("dummy_dds"));

    parser->set_state(parser_start);

    DBG2(cerr << "Parser state: " << states[parser->get_state()] << endl);
}

void DDXParser::ddx_end_document(void * p)
{
    DDXParser *parser = static_cast<DDXParser*>(p);
    DBG2(cerr << "Ending state == " << states[parser->get_state()] <<
         endl);

    if (parser->get_state() != parser_start)
        DDXParser::ddx_fatal_error(parser, "The document contained unbalanced tags.");

    // If we've found any sort of error, don't make the DDX; intern() will
    // take care of the error.
    if (parser->get_state() == parser_error) {
        return;
    }

    // Pop the temporary Structure off the stack and transfer its variables
    // to the DDS.
    Constructor *cp = dynamic_cast < Constructor * >(parser->bt_stack.top());
    if (!cp) {
        delete parser->bt_stack.top();
        parser->bt_stack.pop();
        ddx_fatal_error(parser, "Parse error: Expected a Structure, Sequence or Grid variable.");
        return;
    }

    for (Constructor::Vars_iter i = cp->var_begin(); i != cp->var_end(); ++i) {
        (*i)->set_parent(0);        // top-level vars have no parents
        parser->dds->add_var(*i);
    }

    delete parser->bt_stack.top();
    parser->bt_stack.pop();
}

void DDXParser::ddx_sax2_start_element(void *p,
        const xmlChar *l, const xmlChar *prefix, const xmlChar *URI,
        int nb_namespaces, const xmlChar **namespaces,
        int nb_attributes, int /*nb_defaulted*/, const xmlChar **attributes)
{
    DDXParser *parser = static_cast<DDXParser*>(p);
    const char *localname = (const char *)l;

    DBG2(cerr << "start element: " << localname << ", states: "
         << states[parser->get_state()]);

    switch (parser->get_state()) {
    case parser_start:
        if (strcmp(localname, "Dataset") == 0) {
            parser->set_state(inside_dataset);
            parser->root_ns = URI != 0 ? (const char *)URI: "";
            parser->transfer_xml_attrs(attributes, nb_attributes);

            if (parser->check_required_attribute(string("name")))
                parser->dds->set_dataset_name(parser->attribute_table["name"].value);

            if (parser->check_attribute("dapVersion"))
                parser->dds->set_dap_version(parser->attribute_table["dapVersion"].value);
        }
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected response to start with a Dataset element; found '%s' instead.",
                                       localname);
        break;

    case inside_dataset:
        if (parser->is_attribute_or_alias(localname, attributes, nb_attributes))
            break;
        else if (parser->is_variable(localname, attributes, nb_attributes))
            break;
        else if (strcmp(localname, "blob") == 0 || strcmp(localname, "dataBLOB") == 0) {
            parser->process_blob(attributes, nb_attributes);
            // next state: inside_data_blob
        }
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an Attribute, Alias or variable element; found '%s' instead.",
                                       localname);
        break;

    case inside_attribute_container:
        if (parser->is_attribute_or_alias(localname, attributes, nb_attributes))
            break;
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an Attribute or Alias element; found '%s' instead.",
                                       localname);
        break;

    case inside_attribute:
        if (parser->is_attribute_or_alias(localname, attributes, nb_attributes))
            break;
        else if (strcmp(localname, "value") == 0)
            parser->set_state(inside_attribute_value);
        else
            ddx_fatal_error(parser,
                            "Expected an 'Attribute', 'Alias' or 'value' element; found '%s' instead.",
                            localname);
        break;

    case inside_attribute_value:
        ddx_fatal_error(parser,
                        "Internal parser error; unexpected state, inside value while processing element '%s'.",
                        localname);
        break;

    case inside_other_xml_attribute:
        DBGN(cerr << endl << "\t inside_other_xml_attribute: " << localname << endl);

        parser->other_xml_depth++;

        // Accumulate the elements here

        parser->other_xml.append("<");
        if (prefix) {
            parser->other_xml.append((const char *)prefix);
            parser->other_xml.append(":");
        }
        parser->other_xml.append(localname);

        if (nb_namespaces != 0) {
            parser->transfer_xml_ns(namespaces, nb_namespaces);

            for (map<string,string>::iterator i = parser->namespace_table.begin();
                i != parser->namespace_table.end();
                ++i) {
                parser->other_xml.append(" xmlns");
                if (!i->first.empty()) {
                    parser->other_xml.append(":");
                    parser->other_xml.append(i->first);
                }
                parser->other_xml.append("=\"");
                parser->other_xml.append(i->second);
                parser->other_xml.append("\"");
            }
        }

        if (nb_attributes != 0) {
            parser->transfer_xml_attrs(attributes, nb_attributes);
            for (XMLAttrMap::iterator i = parser->attr_table_begin();
                i != parser->attr_table_end();
                ++i) {
                parser->other_xml.append(" ");
                if (!i->second.prefix.empty()) {
                    parser->other_xml.append(i->second.prefix);
                    parser->other_xml.append(":");
                }
                parser->other_xml.append(i->first);
                parser->other_xml.append("=\"");
                parser->other_xml.append(i->second.value);
                parser->other_xml.append("\"");
            }
        }

        parser->other_xml.append(">");
        break;

    case inside_alias:
        ddx_fatal_error(parser,
                        "Internal parser error; unexpected state, inside alias while processing element '%s'.",
                        localname);
        break;

    case inside_simple_type:
        if (parser->is_attribute_or_alias(localname, attributes, nb_attributes))
            break;
        else
            ddx_fatal_error(parser,
                            "Expected an 'Attribute' or 'Alias' element; found '%s' instead.",
                            localname);
        break;

    case inside_array:
        if (parser->is_attribute_or_alias(localname, attributes, nb_attributes))
            break;
        else if (is_not(localname, "Array")
                && parser->is_variable(localname, attributes, nb_attributes))
            break;
        else if (strcmp(localname, "dimension") == 0) {
            parser->process_dimension(attributes, nb_attributes);
            // next state: inside_dimension
        }
        else
            ddx_fatal_error(parser,
                            "Expected an 'Attribute' or 'Alias' element; found '%s' instead.",
                            localname);
        break;

    case inside_dimension:
        ddx_fatal_error(parser,
                        "Internal parser error; unexpected state, inside dimension while processing element '%s'.",
                        localname);
        break;

    case inside_structure:
        if (parser->is_attribute_or_alias(localname, attributes, nb_attributes))
            break;
        else if (parser->is_variable(localname, attributes, nb_attributes))
            break;
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an Attribute, Alias or variable element; found '%s' instead.",
                                       localname);
        break;

    case inside_sequence:
        if (parser->is_attribute_or_alias(localname, attributes, nb_attributes))
            break;
        else if (parser->is_variable(localname, attributes, nb_attributes))
            break;
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an Attribute, Alias or variable element; found '%s' instead.",
                                       localname);
        break;

    case inside_grid:
        if (parser->is_attribute_or_alias(localname, attributes, nb_attributes))
            break;
        else if (strcmp(localname, "Array") == 0)
            parser->process_variable(dods_array_c, inside_array, attributes, nb_attributes);
        else if (strcmp(localname, "Map") == 0)
            parser->process_variable(dods_array_c, inside_map, attributes, nb_attributes);
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an Attribute, Alias or variable element; found '%s' instead.",
                                       localname);
        break;

    case inside_map:
        if (parser->is_attribute_or_alias(localname, attributes, nb_attributes))
            break;
        else if (is_not(localname, "Array") && is_not(localname, "Sequence")
                 && is_not(localname, "Grid")
                 && parser->is_variable(localname, attributes, nb_attributes))
            break;
        else if (strcmp(localname, "dimension") == 0) {
            parser->process_dimension(attributes, nb_attributes);
            // next state: inside_dimension
        }
        else
            ddx_fatal_error(parser,
                            "Expected an 'Attribute', 'Alias', variable or 'dimension' element; found '%s' instead.",
                            localname);
        break;

    case inside_blob_href:
        ddx_fatal_error(parser,
                        "Internal parser error; unexpected state, inside blob href while processing element '%s'.",
                        localname);
        break;

    case parser_unknown:
        // *** Never used? If so remove/error
        parser->set_state(parser_unknown);
        break;

    case parser_error:
        break;
    }

    DBGN(cerr << " ... " << states[parser->get_state()] << endl);
}

void DDXParser::ddx_sax2_end_element(void *p, const xmlChar *l,
        const xmlChar *prefix, const xmlChar *URI)
{
    DDXParser *parser = static_cast<DDXParser*>(p);
    const char *localname = (const char *)l;

    DBG2(cerr << "End element " << localname << " (state "
         << states[parser->get_state()] << ")" << endl);

    switch (parser->get_state()) {
    case parser_start:
        ddx_fatal_error(parser,
                        "Internal parser error; unexpected state, inside start state while processing element '%s'.",
                        localname);
        break;

    case inside_dataset:
        if (strcmp(localname, "Dataset") == 0)
            parser->pop_state();
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an end Dataset tag; found '%s' instead.",
                                       localname);
        break;

    case inside_attribute_container:
        if (strcmp(localname, "Attribute") == 0) {
            parser->pop_state();
            parser->at_stack.pop();     // pop when leaving a container.
        }
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an end Attribute tag; found '%s' instead.",
                                       localname);
        break;

    case inside_attribute:
        if (strcmp(localname, "Attribute") == 0)
            parser->pop_state();
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an end Attribute tag; found '%s' instead.",
                                       localname);
        break;

    case inside_attribute_value:
        if (strcmp(localname, "value") == 0) {
            parser->pop_state();
            AttrTable *atp = parser->at_stack.top();
            atp->append_attr(parser->dods_attr_name,
                             parser->dods_attr_type, parser->char_data);
            parser->char_data = "";     // Null this after use.
        }
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an end value tag; found '%s' instead.",
                                       localname);

        break;

    case inside_other_xml_attribute: {
            if (strcmp(localname, "Attribute") == 0
                    && parser->root_ns == (const char *)URI) {

                DBGN(cerr << endl << "\t Popping the 'inside_other_xml_attribute' state"
                        << endl);

                parser->pop_state();

                AttrTable *atp = parser->at_stack.top();
                atp->append_attr(parser->dods_attr_name,
                        parser->dods_attr_type, parser->other_xml);

                parser->other_xml = ""; // Null this after use.
            }
            else {
                DBGN(cerr << endl << "\t inside_other_xml_attribute: " << localname
                        << ", depth: " << parser->other_xml_depth << endl);
                if (parser->other_xml_depth == 0)
                    DDXParser::ddx_fatal_error(parser,
                                               "Expected an OtherXML attribute to end! Instead I found '%s'",
                                               localname);
                parser->other_xml_depth--;

                parser->other_xml.append("</");
                if (prefix) {
                    parser->other_xml.append((const char *)prefix);
                    parser->other_xml.append(":");
                }
                parser->other_xml.append(localname);
                parser->other_xml.append(">");
            }
            break;
        }
        // Alias is busted in libdap++ 05/29/03 jhrg
    case inside_alias:
        parser->pop_state();
        break;

    case inside_simple_type: {
        Type t = get_type(localname);
        if (is_simple_type(t)) {
            parser->pop_state();
            BaseType *btp = parser->bt_stack.top();
            parser->bt_stack.pop();
            parser->at_stack.pop();

            BaseType *parent = parser->bt_stack.top();

            if (parent->is_vector_type() || parent->is_constructor_type()) {
                parent->add_var(btp);
                delete btp;
            }
            else {
                DDXParser::ddx_fatal_error(parser,
                                           "Tried to add the simple-type variable '%s' to a non-constructor type (%s %s).",
                                           localname,
                                           parser->bt_stack.top()->
                                           type_name().c_str(),
                                           parser->bt_stack.top()->name().
                                           c_str());
                delete btp;
            }
        }
        else {
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an end tag for a simple type; found '%s' instead.",
                                       localname);
        }
        break;
    }

    case inside_array:
        parser->finish_variable(localname, dods_array_c, "Array");
        break;

    case inside_dimension:
        if (strcmp(localname, "dimension") == 0)
            parser->pop_state();
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an end dimension tag; found '%s' instead.",
                                       localname);
        break;

    case inside_structure:
        parser->finish_variable(localname, dods_structure_c, "Structure");
        break;

    case inside_sequence:
        parser->finish_variable(localname, dods_sequence_c, "Sequence");
        break;

    case inside_grid:
        parser->finish_variable(localname, dods_grid_c, "Grid");
        break;

    case inside_map:
        parser->finish_variable(localname, dods_array_c, "Map");
        break;

    case inside_blob_href:
        if (strcmp(localname, "blob") == 0 || strcmp(localname, "dataBLOB") == 0)
            parser->pop_state();
        else
            DDXParser::ddx_fatal_error(parser,
                                       "Expected an end dataBLOB/blob tag; found '%s' instead.",
                                       localname);
        break;

    case parser_unknown:
        parser->pop_state();
        break;

    case parser_error:
        break;
    }


    DBGN(cerr << " ... " << states[parser->get_state()] << endl);
}

void DDXParser::ddx_get_characters(void * p, const xmlChar * ch, int len)
{
    DDXParser *parser = static_cast<DDXParser*>(p);

    switch (parser->get_state()) {
        case inside_attribute_value:
            parser->char_data.append((const char *)(ch), len);
            DBG2(cerr << "Characters: '" << parser->char_data << "'" << endl);
            break;

        case inside_other_xml_attribute:
            parser->other_xml.append((const char *)(ch), len);
            DBG2(cerr << "Other XML Characters: '" << parser->other_xml << "'" << endl);
            break;

        default:
            break;
    }
}

void DDXParser::ddx_ignoreable_whitespace(void *p, const xmlChar *ch,
        int len)
{
    DDXParser *parser = static_cast<DDXParser*>(p);

    switch (parser->get_state()) {
         case inside_other_xml_attribute:
             parser->other_xml.append((const char *)(ch), len);
             break;

         default:
             break;
    }
}

void DDXParser::ddx_get_cdata(void *p, const xmlChar *value, int len)
{
    DDXParser *parser = static_cast<DDXParser*>(p);

    switch (parser->get_state()) {
         case inside_other_xml_attribute:
             parser->other_xml.append((const char *)(value), len);
             break;

         case parser_unknown:
             break;

         default:
             DDXParser::ddx_fatal_error(parser,
                                        "Found a CData block but none are allowed by DAP.");

             break;
    }
}

xmlEntityPtr DDXParser::ddx_get_entity(void *, const xmlChar * name)
{
    return xmlGetPredefinedEntity(name);
}

void DDXParser::ddx_fatal_error(void * p, const char *msg, ...)
{
    va_list args;
    DDXParser *parser = static_cast<DDXParser*>(p);

    parser->set_state(parser_error);

    va_start(args, msg);
    char str[1024];
    vsnprintf(str, 1024, msg, args);
    va_end(args);

    int line = xmlSAX2GetLineNumber(parser->ctxt);

    parser->error_msg += "At line " + long_to_string(line) + ": ";
    parser->error_msg += string(str) + string("\n");
}


void DDXParser::cleanup_parse(xmlParserCtxtPtr & context)
{
    bool wellFormed = context->wellFormed;
    bool valid = context->valid;

    context->sax = NULL;
    xmlFreeParserCtxt(context);

    // If there's an error, there may still be items on the stack at the
    // end of the parse.
    while (!bt_stack.empty()) {
        delete bt_stack.top();
        bt_stack.pop();
    }

    if (!wellFormed) {
        throw DDXParseFailed(string("The DDX is not a well formed XML document.\n") + error_msg);
    }

    if (!valid) {
        throw DDXParseFailed(string("The DDX is not a valid document.\n") + error_msg);
    }

    if (get_state() == parser_error) {
        throw DDXParseFailed(string("Error parsing DDX response.\n") + error_msg);
    }
}

void DDXParser::intern_stream(istream &in, DDS *dest_dds, string &cid, const string &boundary)
{
    // Code example from libxml2 docs re: read from a stream.
    if (!in || in.eof())
        throw InternalErr(__FILE__, __LINE__, "Input stream not open or read error");

    const int size = 1024;
    char chars[size + 1];

    // int res = fread(chars, 1, 4, in);
    in.read(chars, 4);
    int res = in.gcount();
    if (res > 0) {
        chars[4]='\0';
        xmlParserCtxtPtr context = xmlCreatePushParserCtxt(NULL, NULL, chars, res, "stream");

        if (!context)
            throw DDXParseFailed("Error parsing DDX response: Input does not look like XML");

        ctxt = context;         // need ctxt for error messages
        dds = dest_dds;         // dump values here
        blob_href = &cid;   // cid goes here

        xmlSAXHandler ddx_sax_parser;
        memset( &ddx_sax_parser, 0, sizeof(xmlSAXHandler) );

        ddx_sax_parser.getEntity = &DDXParser::ddx_get_entity;
        ddx_sax_parser.startDocument = &DDXParser::ddx_start_document;
        ddx_sax_parser.endDocument = &DDXParser::ddx_end_document;
        ddx_sax_parser.characters = &DDXParser::ddx_get_characters;
        ddx_sax_parser.ignorableWhitespace = &DDXParser::ddx_ignoreable_whitespace;
        ddx_sax_parser.cdataBlock = &DDXParser::ddx_get_cdata;
        ddx_sax_parser.warning = &DDXParser::ddx_fatal_error;
        ddx_sax_parser.error = &DDXParser::ddx_fatal_error;
        ddx_sax_parser.fatalError = &DDXParser::ddx_fatal_error;
        ddx_sax_parser.initialized = XML_SAX2_MAGIC;
        ddx_sax_parser.startElementNs = &DDXParser::ddx_sax2_start_element;
        ddx_sax_parser.endElementNs = &DDXParser::ddx_sax2_end_element;

        context->sax = &ddx_sax_parser;
        context->userData = this;
        context->validate = true;

        in.getline(chars, size);    // chars has size+1 elements
        res = in.gcount();
        chars[res-1] = '\n';        // libxml needs the newline; w/o it the parse will fail
        chars[res] = '\0';
        while (res > 0 && !is_boundary(chars, boundary)) {
            DBG(cerr << "line (" << res << "): " << chars << endl);
            xmlParseChunk(ctxt, chars, res, 0);

            in.getline(chars, size);    // chars has size+1 elements
            res = in.gcount();
            if (res > 0) {
                chars[res-1] = '\n';
                chars[res] = '\0';
            }
        }

        // This call ends the parse: The fourth argument of xmlParseChunk is
        // the bool 'terminate.'
        xmlParseChunk(ctxt, chars, 0, 1);

        cleanup_parse(context);
    }
    else {
        throw DDXParseFailed("Error parsing DDX response: Could not read from input stream.");
    }
}

void DDXParser::intern_stream(FILE *in, DDS *dest_dds, string &cid, const string &boundary)
{
    // Code example from libxml2 docs re: read from a stream.
    if (!in || feof(in) || ferror(in))
        throw InternalErr(__FILE__, __LINE__, "Input stream not open or read error");

    const int size = 1024;
    char chars[size];

    int res = fread(chars, 1, 4, in);
    if (res > 0) {
        chars[4]='\0';
        xmlParserCtxtPtr context = xmlCreatePushParserCtxt(NULL, NULL, chars, res, "stream");

        if (!context)
            throw DDXParseFailed("Error parsing DDX response: Input does not look like XML");

        ctxt = context;         // need ctxt for error messages
        dds = dest_dds;         // dump values here
        blob_href = &cid;   // cid goes here

        xmlSAXHandler ddx_sax_parser;
        memset( &ddx_sax_parser, 0, sizeof(xmlSAXHandler) );

        ddx_sax_parser.getEntity = &DDXParser::ddx_get_entity;
        ddx_sax_parser.startDocument = &DDXParser::ddx_start_document;
        ddx_sax_parser.endDocument = &DDXParser::ddx_end_document;
        ddx_sax_parser.characters = &DDXParser::ddx_get_characters;
        ddx_sax_parser.ignorableWhitespace = &DDXParser::ddx_ignoreable_whitespace;
        ddx_sax_parser.cdataBlock = &DDXParser::ddx_get_cdata;
        ddx_sax_parser.warning = &DDXParser::ddx_fatal_error;
        ddx_sax_parser.error = &DDXParser::ddx_fatal_error;
        ddx_sax_parser.fatalError = &DDXParser::ddx_fatal_error;
        ddx_sax_parser.initialized = XML_SAX2_MAGIC;
        ddx_sax_parser.startElementNs = &DDXParser::ddx_sax2_start_element;
        ddx_sax_parser.endElementNs = &DDXParser::ddx_sax2_end_element;

        context->sax = &ddx_sax_parser;
        context->userData = this;
        context->validate = true;


        while ((fgets(chars, size, in) != 0) && !is_boundary(chars, boundary)) {
            DBG(cerr << "line (" << strlen(chars) << "): " << chars << endl);
            xmlParseChunk(ctxt, chars, strlen(chars), 0);
        }
        // This call ends the parse: The fourth argument of xmlParseChunk is
        // the bool 'terminate.'
        xmlParseChunk(ctxt, chars, 0, 1);

        cleanup_parse(context);
    }
    else {
        throw DDXParseFailed("Error parsing DDX response: Could not read from input file.");
    }
}


void DDXParser::intern(const string & document, DDS * dest_dds, string &cid)
{
    // Create the context pointer explicitly so that we can store a pointer
    // to it in the DDXParser instance. This provides a way to generate our
    // own error messages *with* line numbers. The messages are pretty
    // meaningless otherwise. This means that we use an interface from the
    // 'parser internals' header, and not the 'parser' header. However, this
    // interface is also used in one of the documented examples, so it's
    // probably pretty stable. 06/02/03 jhrg
    xmlParserCtxtPtr context = xmlCreateFileParserCtxt(document.c_str());
    if (!context)
        throw
        DDXParseFailed(string
                       ("Could not initialize the parser with the file: '")
                       + document + string("'."));

    dds = dest_dds;             // dump values here
    blob_href = &cid;
    ctxt = context;             // need ctxt for error messages

    xmlSAXHandler ddx_sax_parser;
    memset( &ddx_sax_parser, 0, sizeof(xmlSAXHandler) );

    ddx_sax_parser.getEntity = &DDXParser::ddx_get_entity;
    ddx_sax_parser.startDocument = &DDXParser::ddx_start_document;
    ddx_sax_parser.endDocument = &DDXParser::ddx_end_document;
    ddx_sax_parser.characters = &DDXParser::ddx_get_characters;
    ddx_sax_parser.ignorableWhitespace = &DDXParser::ddx_ignoreable_whitespace;
    ddx_sax_parser.cdataBlock = &DDXParser::ddx_get_cdata;
    ddx_sax_parser.warning = &DDXParser::ddx_fatal_error;
    ddx_sax_parser.error = &DDXParser::ddx_fatal_error;
    ddx_sax_parser.fatalError = &DDXParser::ddx_fatal_error;
    ddx_sax_parser.initialized = XML_SAX2_MAGIC;
    ddx_sax_parser.startElementNs = &DDXParser::ddx_sax2_start_element;
    ddx_sax_parser.endElementNs = &DDXParser::ddx_sax2_end_element;

    context->sax = &ddx_sax_parser;
    context->userData = this;
    context->validate = false;

    xmlParseDocument(context);

    cleanup_parse(context);
}

} // namespace libdap