The PlaceholderParser has been rewritten to use

a real boost::spirit::qi parser, accessing the DynamicConfig repository
directly. This is a first step towards a full fledged expression
interpreter.

t/custom_gcode.t

@@ -48,7 +48,7 @@ use Slic3r::Test;
 {
     my $parser = Slic3r::GCode::PlaceholderParser->new;
     $parser->apply_config(my $config = Slic3r::Config::new_from_defaults);
-    $parser->set('foo' => '0');
+    $parser->set('foo' => 0);
     is $parser->process('[temperature_[foo]]'),
         $config->temperature->[0],
         "nested config options";

xs/src/libslic3r/Config.cpp

@@ -234,10 +234,13 @@ bool ConfigBase::set_deserialize_raw(const t_config_option_key &opt_key_src, con
 {
     t_config_option_key opt_key = opt_key_src;
     // Try to deserialize the option by its name.
-    const ConfigOptionDef* optdef = this->def()->get(opt_key);
+    const ConfigDef       *def    = this->def();
+    if (def == nullptr)
+        throw NoDefinitionException();
+    const ConfigOptionDef *optdef = def->get(opt_key);
     if (optdef == nullptr) {
         // If we didn't find an option, look for any other option having this as an alias.
-        for (const auto &opt : this->def()->options) {
+        for (const auto &opt : def->options) {
             for (const t_config_option_key &opt_key2 : opt.second.aliases) {
                 if (opt_key2 == opt_key) {
                     opt_key = opt_key2;
@@ -277,10 +280,16 @@ double ConfigBase::get_abs_value(const t_config_option_key &opt_key) const
         return static_cast<const ConfigOptionFloat*>(raw_opt)->value;
     if (raw_opt->type() == coFloatOrPercent) {
         // Get option definition.
-        const ConfigOptionDef *def = this->def()->get(opt_key);
+        const ConfigDef *def = this->def();
-        assert(def != nullptr);
+        if (def == nullptr)
+            throw NoDefinitionException();
+        const ConfigOptionDef *opt_def = def->get(opt_key);
+        assert(opt_def != nullptr);
         // Compute absolute value over the absolute value of the base option.
-        return static_cast<const ConfigOptionFloatOrPercent*>(raw_opt)->get_abs_value(this->get_abs_value(def->ratio_over));
+        //FIXME there are some ratio_over chains, which end with empty ratio_with.
+        // For example, XXX_extrusion_width parameters are not handled by get_abs_value correctly.
+        return opt_def->ratio_over.empty() ? 0. : 
+            static_cast<const ConfigOptionFloatOrPercent*>(raw_opt)->get_abs_value(this->get_abs_value(opt_def->ratio_over));
     }
     throw std::runtime_error("ConfigBase::get_abs_value(): Not a valid option type for get_abs_value()");
 }
@@ -453,7 +462,10 @@ ConfigOption* DynamicConfig::optptr(const t_config_option_key &opt_key, bool cre
         // Option was not found and a new option shall not be created.
         return nullptr;
     // Try to create a new ConfigOption.
-    const ConfigOptionDef *optdef = this->def()->get(opt_key);
+    const ConfigDef       *def    = this->def();
+    if (def == nullptr)
+        throw NoDefinitionException();
+    const ConfigOptionDef *optdef = def->get(opt_key);
     if (optdef == nullptr)
 //        throw std::runtime_error(std::string("Invalid option name: ") + opt_key);
         // Let the parent decide what to do if the opt_key is not defined by this->def().

xs/src/libslic3r/Config.hpp

@@ -126,6 +126,10 @@ public:
 
     virtual void resize(size_t n, const ConfigOption *opt_default = nullptr) = 0;
 
+    // Get size of this vector.
+    virtual size_t size()  const = 0;
+    // Is this vector empty?
+    virtual bool   empty() const = 0;
 
 protected:
     // Used to verify type compatibility when assigning to / from a scalar ConfigOption.
@@ -140,6 +144,8 @@ public:
     ConfigOptionVector() {}
     explicit ConfigOptionVector(size_t n, const T &value) : values(n, value) {}
     explicit ConfigOptionVector(std::initializer_list<T> il) : values(std::move(il)) {}
+    explicit ConfigOptionVector(const std::vector<T> &values) : values(values) {}
+    explicit ConfigOptionVector(std::vector<T> &&values) : values(std::move(values)) {}
     std::vector<T> values;
     
     void set(const ConfigOption *rhs) override
@@ -227,6 +233,9 @@ public:
         }
     }
 
+    size_t size()  const override { return this->values.size(); }
+    bool   empty() const override { return this->values.empty(); }
+
     bool operator==(const ConfigOption &rhs) const override
     {
         if (rhs.type() != this->type())
@@ -445,6 +454,8 @@ class ConfigOptionStrings : public ConfigOptionVector<std::string>
 public:
     ConfigOptionStrings() : ConfigOptionVector<std::string>() {}
     explicit ConfigOptionStrings(size_t n, const std::string &value) : ConfigOptionVector<std::string>(n, value) {}
+    explicit ConfigOptionStrings(const std::vector<std::string> &values) : ConfigOptionVector<std::string>(values) {}
+    explicit ConfigOptionStrings(std::vector<std::string> &&values) : ConfigOptionVector<std::string>(std::move(values)) {}
     explicit ConfigOptionStrings(std::initializer_list<std::string> il) : ConfigOptionVector<std::string>(std::move(il)) {}
 
     static ConfigOptionType static_type() { return coStrings; }
@@ -1049,23 +1060,71 @@ private:
 class DynamicConfig : public virtual ConfigBase
 {
 public:
+    DynamicConfig() {}
     DynamicConfig(const DynamicConfig& other) { *this = other; }
     DynamicConfig(DynamicConfig&& other) : options(std::move(other.options)) { other.options.clear(); }
     virtual ~DynamicConfig() { clear(); }
 
-    DynamicConfig& operator=(const DynamicConfig &other) 
+    // Copy a content of one DynamicConfig to another DynamicConfig.
+    // If rhs.def() is not null, then it has to be equal to this->def(). 
+    DynamicConfig& operator=(const DynamicConfig &rhs) 
     {
+        assert(this->def() == nullptr || this->def() == rhs.def());
         this->clear();
-        for (const auto &kvp : other.options)
+        for (const auto &kvp : rhs.options)
             this->options[kvp.first] = kvp.second->clone();
         return *this;
     }
 
-    DynamicConfig& operator=(DynamicConfig &&other) 
+    // Move a content of one DynamicConfig to another DynamicConfig.
+    // If rhs.def() is not null, then it has to be equal to this->def(). 
+    DynamicConfig& operator=(DynamicConfig &&rhs) 
     {
+        assert(this->def() == nullptr || this->def() == rhs.def());
         this->clear();
-        this->options = std::move(other.options);
+        this->options = std::move(rhs.options);
-        other.options.clear();
+        rhs.options.clear();
+        return *this;
+    }
+
+    // Add a content of one DynamicConfig to another DynamicConfig.
+    // If rhs.def() is not null, then it has to be equal to this->def().
+    DynamicConfig& operator+=(const DynamicConfig &rhs)
+    {
+        assert(this->def() == nullptr || this->def() == rhs.def());
+        for (const auto &kvp : rhs.options) {
+            auto it = this->options.find(kvp.first);
+            if (it == this->options.end())
+                this->options[kvp.first] = kvp.second->clone();
+            else {
+                assert(it->second->type() == kvp.second->type());
+                if (it->second->type() == kvp.second->type())
+                    *it->second = *kvp.second;
+                else {
+                    delete it->second;
+                    it->second = kvp.second->clone();
+                }
+            }
+        }
+        return *this;
+    }
+
+    // Move a content of one DynamicConfig to another DynamicConfig.
+    // If rhs.def() is not null, then it has to be equal to this->def().
+    DynamicConfig& operator+=(DynamicConfig &&rhs) 
+    {
+        assert(this->def() == nullptr || this->def() == rhs.def());
+        for (const auto &kvp : rhs.options) {
+            auto it = this->options.find(kvp.first);
+            if (it == this->options.end()) {
+                this->options[kvp.first] = kvp.second;
+            } else {
+                assert(it->second->type() == kvp.second->type());
+                delete it->second;
+                it->second = kvp.second;
+            }
+        }
+        rhs.options.clear();
         return *this;
     }
 
@@ -1094,6 +1153,9 @@ public:
         return true;
     }
 
+    // Allow DynamicConfig to be instantiated on ints own without a definition.
+    // If the definition is not defined, the method requiring the definition will throw NoDefinitionException.
+    const ConfigDef*        def() const override { return nullptr; };
     template<class T> T*    opt(const t_config_option_key &opt_key, bool create = false)
         { return dynamic_cast<T*>(this->option(opt_key, create)); }
     // Overrides ConfigBase::optptr(). Find ando/or create a ConfigOption instance for a given name.
@@ -1101,6 +1163,22 @@ public:
     // Overrides ConfigBase::keys(). Collect names of all configuration values maintained by this configuration store.
     t_config_option_keys    keys() const override;
 
+    // Set a value for an opt_key. Returns true if the value did not exist yet.
+    // This DynamicConfig will take ownership of opt.
+    // Be careful, as this method does not test the existence of opt_key in this->def().
+    bool                    set_key_value(const std::string &opt_key, ConfigOption *opt)
+    {
+        auto it = this->options.find(opt_key);
+        if (it == this->options.end()) {
+            this->options[opt_key] = opt;
+            return true;
+        } else {
+            delete it->second;
+            it->second = opt;
+            return false;
+        }
+    }
+
     std::string&        opt_string(const t_config_option_key &opt_key, bool create = false)     { return this->option<ConfigOptionString>(opt_key, create)->value; }
     const std::string&  opt_string(const t_config_option_key &opt_key) const                    { return const_cast<DynamicConfig*>(this)->opt_string(opt_key); }
     std::string&        opt_string(const t_config_option_key &opt_key, unsigned int idx)        { return this->option<ConfigOptionStrings>(opt_key)->get_at(idx); }
@@ -1119,9 +1197,6 @@ public:
     bool                opt_bool(const t_config_option_key &opt_key) const                      { return this->option<ConfigOptionBool>(opt_key)->value != 0; }
     bool                opt_bool(const t_config_option_key &opt_key, unsigned int idx) const    { return this->option<ConfigOptionBools>(opt_key)->get_at(idx) != 0; }
 
-protected:
-    DynamicConfig() {}
-
 private:
     typedef std::map<t_config_option_key,ConfigOption*> t_options_map;
     t_options_map options;
@@ -1150,6 +1225,13 @@ public:
     const char* what() const noexcept override { return "Unknown config option"; }
 };
 
+/// Indicate that the ConfigBase derived class does not provide config definition (the method def() returns null).
+class NoDefinitionException : public std::exception
+{
+public:
+    const char* what() const noexcept override { return "No config definition"; }
+};
+
 }
 
 #endif

xs/src/libslic3r/GCode.cpp

@@ -887,18 +887,22 @@ void GCode::process_layer(
 
     // Set new layer - this will change Z and force a retraction if retract_layer_change is enabled.
     if (! print.config.before_layer_gcode.value.empty()) {
-        PlaceholderParser pp(m_placeholder_parser);
+        DynamicConfig config;
-        pp.set("layer_num", m_layer_index + 1);
+        config.set_key_value("layer_num", new ConfigOptionInt(m_layer_index + 1));
-        pp.set("layer_z",   print_z);
+        config.set_key_value("layer_z",   new ConfigOptionFloat(print_z));
-        gcode += pp.process(print.config.before_layer_gcode.value, m_writer.extruder()->id()) + "\n";
+        gcode += m_placeholder_parser.process(
+            print.config.before_layer_gcode.value, m_writer.extruder()->id(), &config)
+            + "\n";
     }
     gcode += this->change_layer(print_z);  // this will increase m_layer_index
 	m_layer = &layer;
     if (! print.config.layer_gcode.value.empty()) {
-        PlaceholderParser pp(m_placeholder_parser);
+        DynamicConfig config;
-        pp.set("layer_num", m_layer_index);
+        config.set_key_value("layer_num", new ConfigOptionInt(m_layer_index));
-        pp.set("layer_z",   print_z);
+        config.set_key_value("layer_z",   new ConfigOptionFloat(print_z));
-        gcode += pp.process(print.config.layer_gcode.value, m_writer.extruder()->id()) + "\n";
+        gcode += m_placeholder_parser.process(
+            print.config.layer_gcode.value, m_writer.extruder()->id(), &config)
+            + "\n";
     }
 
     if (! first_layer && ! m_second_layer_things_done) {
@@ -2091,10 +2095,12 @@ std::string GCode::set_extruder(unsigned int extruder_id)
     
     // append custom toolchange G-code
     if (m_writer.extruder() != nullptr && !m_config.toolchange_gcode.value.empty()) {
-        PlaceholderParser pp = m_placeholder_parser;
+        DynamicConfig config;
-        pp.set("previous_extruder", m_writer.extruder()->id());
+        config.set_key_value("previous_extruder", new ConfigOptionInt((int)m_writer.extruder()->id()));
-        pp.set("next_extruder",     extruder_id);
+        config.set_key_value("next_extruder",     new ConfigOptionInt((int)extruder_id));
-        gcode += pp.process(m_config.toolchange_gcode.value, extruder_id) + '\n';
+        gcode += m_placeholder_parser.process(
+            m_config.toolchange_gcode.value, extruder_id, &config)
+            + '\n';
     }
     
     // if ooze prevention is enabled, park current extruder in the nearest

xs/src/libslic3r/PlaceholderParser.cpp

@@ -21,6 +21,29 @@
     #endif
 #endif
 
+// Spirit v2.5 allows you to suppress automatic generation
+// of predefined terminals to speed up complation. With
+// BOOST_SPIRIT_NO_PREDEFINED_TERMINALS defined, you are
+// responsible in creating instances of the terminals that
+// you need (e.g. see qi::uint_type uint_ below).
+//#define BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
+
+#include <boost/config/warning_disable.hpp>
+#include <boost/lexical_cast.hpp>
+#include <boost/spirit/include/qi.hpp>
+#include <boost/spirit/include/qi_lit.hpp>
+#include <boost/spirit/include/phoenix_core.hpp>
+#include <boost/spirit/include/phoenix_operator.hpp>
+#include <boost/spirit/include/phoenix_fusion.hpp>
+#include <boost/spirit/include/phoenix_stl.hpp>
+#include <boost/spirit/include/phoenix_object.hpp>
+#include <boost/fusion/include/adapt_struct.hpp>
+#include <boost/variant/recursive_variant.hpp>
+#include <boost/phoenix/bind/bind_function.hpp>
+
+#include <iostream>
+#include <string>
+
 namespace Slic3r {
 
 PlaceholderParser::PlaceholderParser()
@@ -61,130 +84,398 @@ void PlaceholderParser::update_timestamp()
 // are expected to be addressed by the extruder ID, therefore
 // if a vector configuration value is addressed without an index,
 // a current extruder ID is used.
-void PlaceholderParser::apply_config(const DynamicPrintConfig &config)
+void PlaceholderParser::apply_config(const DynamicPrintConfig &rhs)
 {
-    for (const t_config_option_key &opt_key : config.keys()) {
+    const ConfigDef *def = rhs.def();
-        const ConfigOptionDef* def = config.def()->get(opt_key);
+    for (const t_config_option_key &opt_key : rhs.keys()) {
-        if (def->multiline || opt_key == "post_process")
+        const ConfigOptionDef *opt_def = def->get(opt_key);
+        if (opt_def->multiline || opt_key == "post_process")
             continue;
-
+        const ConfigOption *opt = rhs.option(opt_key);
-        const ConfigOption* opt = config.option(opt_key);
+        // Store a copy of the config option.
-        const ConfigOptionVectorBase* optv = dynamic_cast<const ConfigOptionVectorBase*>(opt);
+        // Convert FloatOrPercent values to floats first.
-        if (optv != nullptr && opt_key != "bed_shape") {
+        //FIXME there are some ratio_over chains, which end with empty ratio_with.
-            // set placeholders for options with multiple values
+        // For example, XXX_extrusion_width parameters are not handled by get_abs_value correctly.
-            this->set(opt_key, optv->vserialize());
+        this->set(opt_key, (opt->type() == coFloatOrPercent) ?
-        } else if (const ConfigOptionPoint* optp = dynamic_cast<const ConfigOptionPoint*>(opt)) {
+            new ConfigOptionFloat(rhs.get_abs_value(opt_key)) :
-            this->set(opt_key, optp->serialize());
+            opt->clone());
-            Pointf val = *optp;
-            this->set(opt_key + "_X", val.x);
-            this->set(opt_key + "_Y", val.y);
-        } else {
-            // set single-value placeholders
-            this->set(opt_key, opt->serialize());
-        }
     }
 }
 
 void PlaceholderParser::apply_env_variables()
 {
-    for (char** env = environ; *env; env++) {
+    for (char** env = environ; *env; ++ env) {
         if (strncmp(*env, "SLIC3R_", 7) == 0) {
             std::stringstream ss(*env);
             std::string key, value;
             std::getline(ss, key, '=');
             ss >> value;
-            
             this->set(key, value);
         }
     }
 }
 
-void PlaceholderParser::set(const std::string &key, const std::string &value)
+namespace client
 {
-    m_single[key] = value;
+    struct MyContext {
-    m_multiple.erase(key);
+        const PlaceholderParser *pp = nullptr;
+        const DynamicConfig     *config_override = nullptr;
+        const size_t             current_extruder_id = 0;
+
+        const ConfigOption*     resolve_symbol(const std::string &opt_key) const
+        {
+            const ConfigOption *opt = nullptr;
+            if (config_override != nullptr)
+                opt = config_override->option(opt_key);
+            if (opt == nullptr)
+                opt = pp->option(opt_key);
+            return opt;
         }
 
-void PlaceholderParser::set(const std::string &key, int value)
+        template <typename Iterator>
+        static void legacy_variable_expansion(
+            const MyContext                 *ctx, 
+            boost::iterator_range<Iterator> &opt_key,
+            std::string                     &output)
         {
-    std::ostringstream ss;
+            std::string         opt_key_str(opt_key.begin(), opt_key.end());
-    ss << value;
+            const ConfigOption *opt = ctx->resolve_symbol(opt_key_str);
-    this->set(key, ss.str());
+            size_t              idx = ctx->current_extruder_id;
+            if (opt == nullptr) {
+                // Check whether this is a legacy vector indexing.
+                idx = opt_key_str.rfind('_');
+                if (idx != std::string::npos) {
+                    opt = ctx->resolve_symbol(opt_key_str.substr(0, idx));
+                    if (opt != nullptr) {
+                        if (! opt->is_vector())
+                            boost::throw_exception(boost::spirit::qi::expectation_failure<Iterator>(
+                                opt_key.begin(), opt_key.end(), boost::spirit::info("Trying to index a scalar variable")));
+                        char *endptr = nullptr;
+                        idx = strtol(opt_key_str.c_str() + idx + 1, &endptr, 10);
+                        if (endptr == nullptr || *endptr != 0)
+                            boost::throw_exception(boost::spirit::qi::expectation_failure<Iterator>(
+                                opt_key.begin() + idx + 1, opt_key.end(), boost::spirit::info("Invalid vector index")));
+                    }
+                }
+            }
+            if (opt == nullptr)
+                boost::throw_exception(boost::spirit::qi::expectation_failure<Iterator>(
+                    opt_key.begin(), opt_key.end(), boost::spirit::info("Variable does not exist")));
+            if (opt->is_scalar())
+                output = opt->serialize();
+            else {
+                const ConfigOptionVectorBase *vec = static_cast<const ConfigOptionVectorBase*>(opt);
+                if (vec->empty())
+                    boost::throw_exception(boost::spirit::qi::expectation_failure<Iterator>(
+                        opt_key.begin(), opt_key.end(), boost::spirit::info("Indexing an empty vector variable")));
+                output = vec->vserialize()[(idx >= vec->size()) ? 0 : idx];
+            }
         }
 
-void PlaceholderParser::set(const std::string &key, unsigned int value)
+        template <typename Iterator>
+        static void legacy_variable_expansion2(
+            const MyContext                 *ctx, 
+            boost::iterator_range<Iterator> &opt_key,
+            boost::iterator_range<Iterator> &opt_vector_index,
+            std::string                     &output)
         {
-    std::ostringstream ss;
+            std::string         opt_key_str(opt_key.begin(), opt_key.end());
-    ss << value;
+            const ConfigOption *opt = ctx->resolve_symbol(opt_key_str);
-    this->set(key, ss.str());
+            if (opt == nullptr) {
+                // Check whether the opt_key ends with '_'.
+                if (opt_key_str.back() == '_')
+                    opt_key_str.resize(opt_key_str.size() - 1);
+                opt = ctx->resolve_symbol(opt_key_str);
+            }
+            if (! opt->is_vector())
+                boost::throw_exception(boost::spirit::qi::expectation_failure<Iterator>(
+                    opt_key.begin(), opt_key.end(), boost::spirit::info("Trying to index a scalar variable")));
+            const ConfigOptionVectorBase *vec = static_cast<const ConfigOptionVectorBase*>(opt);
+            if (vec->empty())
+                boost::throw_exception(boost::spirit::qi::expectation_failure<Iterator>(
+                    opt_key.begin(), opt_key.end(), boost::spirit::info("Indexing an empty vector variable")));
+            const ConfigOption *opt_index = ctx->resolve_symbol(std::string(opt_vector_index.begin(), opt_vector_index.end()));
+            if (opt_index == nullptr)
+                boost::throw_exception(boost::spirit::qi::expectation_failure<Iterator>(
+                    opt_key.begin(), opt_key.end(), boost::spirit::info("Variable does not exist")));
+            if (opt_index->type() != coInt)
+                boost::throw_exception(boost::spirit::qi::expectation_failure<Iterator>(
+                    opt_key.begin(), opt_key.end(), boost::spirit::info("Indexing variable has to be integer")));
+			int idx = opt_index->getInt();
+			if (idx < 0)
+				boost::throw_exception(boost::spirit::qi::expectation_failure<Iterator>(
+					opt_key.begin(), opt_key.end(), boost::spirit::info("Negative vector index")));
+			output = vec->vserialize()[(idx >= (int)vec->size()) ? 0 : idx];
+        }
+    };
+
+    struct expr
+    {
+        expr(int i = 0) : type(TYPE_INT) { data.i = i; }
+        expr(double d) : type(TYPE_DOUBLE) { data.d = d; }
+        expr(const char *s) : type(TYPE_STRING) { data.s = new std::string(s); }
+        expr(std::string &s) : type(TYPE_STRING) { data.s = new std::string(s); }
+        expr(const expr &rhs) : type(rhs.type) { data.s = (rhs.type == TYPE_STRING) ? new std::string(*rhs.data.s) : rhs.data.s; }
+        expr(expr &&rhs) : type(rhs.type) { data.s = rhs.data.s; rhs.data.s = nullptr; rhs.type = TYPE_EMPTY; }
+        ~expr() { if (type == TYPE_STRING) delete data.s; data.s = nullptr; }
+
+        expr &operator=(const expr &rhs) 
+        { 
+            type = rhs.type; 
+            data.s = (type == TYPE_STRING) ? new std::string(*rhs.data.s) : rhs.data.s; 
+            return *this; 
         }
 
-void PlaceholderParser::set(const std::string &key, double value)
+        expr &operator=(expr &&rhs) 
         { 
-    std::ostringstream ss;
+            type = rhs.type; 
-    ss << value;
+            data.s = rhs.data.s; 
-    this->set(key, ss.str());
+            rhs.data.s = nullptr; 
+            rhs.type = TYPE_EMPTY; 
+            return *this; 
         }
 
-void PlaceholderParser::set(const std::string &key, std::vector<std::string> values)
+        int&                i()       { return data.i; }
+        int                 i() const { return data.i; }
+        double&             d()       { return data.d; }
+        double              d() const { return data.d; }
+        std::string&        s()       { return *data.s; }
+        const std::string&  s() const { return *data.s; }
+        
+        std::string         to_string() const 
         {
-    m_single.erase(key);
+            std::string out;
-    if (values.empty())
+            switch (type) {
-        m_multiple.erase(key);
+            case TYPE_INT:    out = boost::to_string(data.i); break;
+            case TYPE_DOUBLE: out = boost::to_string(data.d); break;
+            case TYPE_STRING: out = *data.s; break;
+            }
+            return out;
+        }
+
+        union {
+            int          i;
+            double       d;
+            std::string *s;
+        } data;
+
+        enum Type {
+            TYPE_EMPTY = 0,
+            TYPE_INT,
+            TYPE_DOUBLE,
+            TYPE_STRING,
+        };
+
+        int type;
+    };
+
+    ///////////////////////////////////////////////////////////////////////////
+    //  Our calculator grammar
+    ///////////////////////////////////////////////////////////////////////////
+    template <typename Iterator>
+    struct calculator : boost::spirit::qi::grammar<Iterator, std::string(const MyContext*), boost::spirit::ascii::space_type>
+    {
+        calculator() : calculator::base_type(start)
+        {
+            using boost::spirit::qi::alpha;
+            using boost::spirit::qi::alnum;
+            using boost::spirit::qi::eol;
+            using boost::spirit::qi::eoi;
+            using boost::spirit::qi::eps;
+            using boost::spirit::qi::raw;
+            using boost::spirit::qi::lit;
+            using boost::spirit::qi::lexeme;
+            using boost::spirit::qi::on_error;
+            using boost::spirit::qi::fail;
+            using boost::spirit::ascii::char_;
+            using boost::spirit::int_;
+            using boost::spirit::double_;
+            using boost::spirit::ascii::string;
+            using namespace boost::spirit::qi::labels;
+
+            using boost::phoenix::construct;
+            using boost::phoenix::val;
+            using boost::phoenix::begin;
+
+            boost::spirit::qi::_val_type _val;
+            boost::spirit::qi::_1_type _1;
+            boost::spirit::qi::_2_type _2;
+            boost::spirit::qi::_r1_type _r1;
+            boost::spirit::qi::uint_type uint_;
+
+            // Starting symbol of the grammer.
+            // The leading eps is required by the "expectation point" operator ">".
+            // Without it, some of the errors would not trigger the error handler.
+            start = eps > *(text [_val+=_1]
+                || ((lit('{') > macro [_val+=_1] > '}') 
+                | (lit('[') > legacy_variable_expansion(_r1) [_val+=_1] > ']')));
+            start.name("start");
+
+            // Free-form text up to a first brace, including spaces and newlines.
+            // The free-form text will be inserted into the processed text without a modification.
+            text = raw[+(char_ - '[' - '{')];
+            text.name("text");
+
+            // New style of macro expansion.
+            // The macro expansion may contain numeric or string expressions, ifs and cases.
+            macro = identifier;
+            macro.name("macro");
+
+            // Legacy variable expansion of the original Slic3r, in the form of [scalar_variable] or [vector_variable_index].
+            legacy_variable_expansion =
+                    (identifier >> &lit(']'))
+                        [ boost::phoenix::bind(&MyContext::legacy_variable_expansion<Iterator>, _r1, _1, _val) ]
+                |   (identifier > lit('[') > identifier > ']') 
+                        [ boost::phoenix::bind(&MyContext::legacy_variable_expansion2<Iterator>, _r1, _1, _2, _val) ]
+                ;
+            legacy_variable_expansion.name("legacy_variable_expansion");
+
+            identifier =
+//                    !expr.keywords >>  
+                raw[lexeme[(alpha | '_') >> *(alnum | '_')]]
+                ;
+            identifier.name("identifier");
+
+/*
+            bool_expr =
+                (expression >> '=' >> '=' >> expression) |
+                (expression >> '!' >> '=' >> expression) |
+                (expression >> '<' >> '>' >> expression)
+                ;
+
+            expression =
+                term                            //[_val = _1]
+                >> *(   ('+' >> term            ) //[_val += _1])
+                    |   ('-' >> term            )//[_val -= _1])
+                    )
+                ;
+
+            term =
+                factor                          //[_val = _1]
+                >> *(   ('*' >> factor          )//[_val *= _1])
+                    |   ('/' >> factor          )//[_val /= _1])
+                    )
+                ;
+
+            factor =
+                    int_                        //[_val = expr(_1)]
+                |   double_                     //[_val = expr(_1)]
+                |   '(' >> expression           >> ')' // [_val = std::move(_1)] >> ')'
+                |   ('-' >> factor              ) //[_val = -_1])
+                |   ('+' >> factor              ) //[_val = std::move(_1)])
+                ;
+*/
+
+//            text %= lexeme[+(char_ - '<')];
+
+//            text_to_eol %= lexeme[*(char_ - eol) >> (eol | eoi)];
+            /*
+            expression_with_braces = lit('{') >> (
+                string("if")     >> if_else_output [_val = _1] |
+                string("switch") >> switch_output  [_val = _1] |
+                expression [_val = boost::to_string(_1)] >> '}'
+                );
+            if_else_output = 
+                bool_expr[_r1 = _1] >> '}' >> text_to_eol[_val = _r1 ? _1 : std::string()] >>
+                    *(lit('{') >> "elsif" >> bool_expr[_r1 = !_r1 && _1] >> '}' >> text_to_eol[_val = _r1 ? _1 : std::string()]) >>
+                    -(lit('{') >> "else" >> '}' >> text_to_eol[_val = _r1 ? std::string() : _1]);
+*/
+/*
+            on_error<fail>(start, 
+                    phx::ref(std::cout)
+                       << "Error! Expecting "
+                       << boost::spirit::qi::_4
+                       << " here: '"
+                       << construct<std::string>(boost::spirit::qi::_3, boost::spirit::qi::_2)
+                       << "'\n"
+                );
+*/
+        }
+
+        // The start of the grammar.
+        boost::spirit::qi::rule<Iterator, std::string(const MyContext*), boost::spirit::ascii::space_type> start;
+        // A free-form text.
+        boost::spirit::qi::rule<Iterator, std::string(), boost::spirit::ascii::space_type> text;
+        // Statements enclosed in curely braces {}
+        boost::spirit::qi::rule<Iterator, std::string(), boost::spirit::ascii::space_type> macro;
+        // Legacy variable expansion of the original Slic3r, in the form of [scalar_variable] or [vector_variable_index].
+        boost::spirit::qi::rule<Iterator, std::string(const MyContext*), boost::spirit::ascii::space_type> legacy_variable_expansion;
+        // Parsed identifier name.
+        boost::spirit::qi::rule<Iterator,  boost::iterator_range<Iterator>, boost::spirit::ascii::space_type> identifier;
+
+        boost::spirit::qi::rule<Iterator, expr(), boost::spirit::ascii::space_type> expression, term, factor;
+        boost::spirit::qi::rule<Iterator, std::string(), boost::spirit::ascii::space_type> text_to_eol;
+        boost::spirit::qi::rule<Iterator, std::string(bool), boost::spirit::ascii::space_type> expression_with_braces;
+        boost::spirit::qi::rule<Iterator, bool, boost::spirit::ascii::space_type> bool_expr;
+
+        boost::spirit::qi::rule<Iterator, std::string(bool), boost::spirit::ascii::space_type> if_else_output;
+        boost::spirit::qi::rule<Iterator, std::string(expr), boost::spirit::ascii::space_type> switch_output;
+    };
+}
+
+struct printer
+{
+    typedef boost::spirit::utf8_string string;
+
+    void element(string const& tag, string const& value, int depth) const
+    {
+        for (int i = 0; i < (depth*4); ++i) // indent to depth
+            std::cout << ' ';
+        std::cout << "tag: " << tag;
+        if (value != "")
+            std::cout << ", value: " << value;
+        std::cout << std::endl;
+    }
+};
+
+void print_info(boost::spirit::info const& what)
+{
+    using boost::spirit::basic_info_walker;
+    printer pr;
+    basic_info_walker<printer> walker(pr, what.tag, 0);
+    boost::apply_visitor(walker, what.value);
+}
+
+std::string PlaceholderParser::process(const std::string &templ, unsigned int current_extruder_id, const DynamicConfig *config_override) const
+{
+    typedef std::string::const_iterator iterator_type;
+    typedef client::calculator<iterator_type> calculator;
+
+    boost::spirit::ascii::space_type space; // Our skipper
+    calculator calc; // Our grammar
+
+    std::string::const_iterator iter = templ.begin();
+    std::string::const_iterator end = templ.end();
+    //std::string result;
+    std::string result;
+    bool r = false;
+    try {
+        client::MyContext context;
+        context.pp = this;
+        context.config_override = config_override;
+        r = phrase_parse(iter, end, calc(&context), space, result);
+    } catch (boost::spirit::qi::expectation_failure<iterator_type> const& x) {
+        std::cout << "expected: "; print_info(x.what_);
+        std::cout << "got: \"" << std::string(x.first, x.last) << '"' << std::endl;
+    }
+
+    if (r && iter == end)
+    {
+//        std::cout << "-------------------------\n";
+//        std::cout << "Parsing succeeded\n";
+//        std::cout << "result = " << result << std::endl;
+//        std::cout << "-------------------------\n";
+    }
     else
-        m_multiple[key] = values;
-}
-
-std::string PlaceholderParser::process(std::string str, unsigned int current_extruder_id) const
     {
-    char key[2048];
+        std::string rest(iter, end);
-
+        std::cout << "-------------------------\n";
-    // Replace extruder independent single options, like [foo].
+        std::cout << "Parsing failed\n";
-    for (const auto &key_value : m_single) {
+        std::cout << "stopped at: \" " << rest << "\"\n";
-        sprintf(key, "[%s]", key_value.first.c_str());
+        std::cout << "source: \n" << templ;       
-        const std::string &replace = key_value.second;
+        std::cout << "-------------------------\n";
-        for (size_t i = 0; (i = str.find(key, i)) != std::string::npos;) {
-            str.replace(i, key_value.first.size() + 2, replace);
-            i += replace.size();
     }
-    }
+    return result;
-
-    // Replace extruder dependent single options with the value for the active extruder.
-    // For example, [temperature] will be replaced with the current extruder temperature.
-    for (const auto &key_value : m_multiple) {
-		sprintf(key, "[%s]", key_value.first.c_str());
-        const std::string &replace = key_value.second[(current_extruder_id < key_value.second.size()) ? current_extruder_id : 0];
-        for (size_t i = 0; (i = str.find(key, i)) != std::string::npos;) {
-            str.replace(i, key_value.first.size() + 2, replace);
-            i += replace.size();
-        }
-    }
-
-    // Replace multiple options like [foo_0].
-    for (const auto &key_value : m_multiple) {
-        sprintf(key, "[%s_", key_value.first.c_str());
-        const std::vector<std::string> &values = key_value.second;
-        for (size_t i = 0; (i = str.find(key, i)) != std::string::npos;) {
-            size_t k = str.find(']', i + key_value.first.size() + 2);
-            if (k != std::string::npos) {
-                // Parse the key index and the closing bracket.
-                ++ k;
-                int idx = 0;
-                if (sscanf(str.c_str() + i + key_value.first.size() + 2, "%d]", &idx) == 1 && idx >= 0) {
-                    if (idx >= int(values.size()))
-                        idx = 0;
-                    str.replace(i, k - i, values[idx]);
-                    i += values[idx].size();
-                    continue;
-                }
-            }
-            // The key does not match the pattern [foo_%d]. Skip just [foo_.] with the hope that there was a missing ']',
-            // so an opening '[' may be found somewhere before the position k.
-            i += key_value.first.size() + 3;
-        }
-    }
-    
-    return str;
 }
 
 }

xs/src/libslic3r/PlaceholderParser.hpp

@@ -12,22 +12,26 @@ namespace Slic3r {
 class PlaceholderParser
 {
 public:    
-    std::map<std::string, std::string>                  m_single;
-    std::map<std::string, std::vector<std::string>>     m_multiple;
-    
     PlaceholderParser();
+    
     void update_timestamp();
     void apply_config(const DynamicPrintConfig &config);
     void apply_env_variables();
-    void set(const std::string &key, const std::string &value);
+
-    void set(const std::string &key, int value);
+    // Add new ConfigOption values to m_config.
-    void set(const std::string &key, unsigned int value);
+    void set(const std::string &key, const std::string &value)  { this->set(key, new ConfigOptionString(value)); }
-    void set(const std::string &key, double value);
+    void set(const std::string &key, int value)                 { this->set(key, new ConfigOptionInt(value)); }
-    void set(const std::string &key, std::vector<std::string> values);
+    void set(const std::string &key, unsigned int value)        { this->set(key, int(value)); }
-    std::string process(std::string str, unsigned int current_extruder_id) const;
+    void set(const std::string &key, double value)              { this->set(key, new ConfigOptionFloat(value)); }
+    void set(const std::string &key, const std::vector<std::string> &values) { this->set(key, new ConfigOptionStrings(values)); }
+    void set(const std::string &key, ConfigOption *opt)         { m_config.set_key_value(key, opt); }
+    const ConfigOption* option(const std::string &key) const    { return m_config.option(key); }
+
+    // Fill in the template.
+    std::string process(const std::string &templ, unsigned int current_extruder_id, const DynamicConfig *config_override = nullptr) const;
     
 private:
-    bool find_and_replace(std::string &source, std::string const &find, std::string const &replace) const;
+    DynamicConfig m_config;
 };
 
 }

xs/xsp/PlaceholderParser.xsp

@@ -9,15 +9,10 @@
 %name{Slic3r::GCode::PlaceholderParser} class PlaceholderParser {
     PlaceholderParser();
     ~PlaceholderParser();
-    Clone<PlaceholderParser> clone()
-        %code{% RETVAL = THIS; %};
     
-    void update_timestamp();
-    void apply_env_variables();
     void apply_config(DynamicPrintConfig *config)
         %code%{ THIS->apply_config(*config); %};
-    void set(std::string key, std::string value);
+    void set(std::string key, int value);
-    %name{set_multiple} void set(std::string key, std::vector<std::string> values);
     std::string process(std::string str) const
         %code%{ RETVAL = THIS->process(str, 0); %};
 };