WIP PlaceholderParser: Support for local and global variables.

Implements #4048 #7196

Syntax:

(global|local) variable_name =
	(scalar_expression|vector_variable|array_expr|initializer_list)

array_expr := array(repeat, value)
initializer_list := (value, value, value, ...)

The type of the newly created variable is defined by the type
of the right hand side intitializer.

Newly declared variable must not override an existing variable.
Variable may be assigned with global|local expression, but its type
must not be changed.

Newly the assignment operator also accepts the same right hand expressions
as the global|local variable definition.

src/libslic3r/GCode.cpp

@@ -1086,6 +1086,8 @@ void GCode::_do_export(Print& print, GCodeOutputStream &file, ThumbnailsGenerato
     m_placeholder_parser = print.placeholder_parser();
     m_placeholder_parser.update_timestamp();
     m_placeholder_parser_context.rng = std::mt19937(std::chrono::high_resolution_clock::now().time_since_epoch().count());
+    // Enable passing global variables between PlaceholderParser invocations.
+    m_placeholder_parser_context.global_config = std::make_unique<DynamicConfig>();
     print.update_object_placeholders(m_placeholder_parser.config_writable(), ".gcode");
 
     // Get optimal tool ordering to minimize tool switches of a multi-exruder print.

src/libslic3r/PlaceholderParser.cpp

@@ -191,6 +191,10 @@ namespace client
     struct expr
     {
                  expr() {}
+                 expr(const expr &rhs) : m_type(rhs.type()), it_range(rhs.it_range)
+                    { if (rhs.type() == TYPE_STRING) m_data.s = new std::string(*rhs.m_data.s); else m_data.set(rhs.m_data); }
+                 expr(expr &&rhs) : expr(std::move(rhs), rhs.it_range.begin(), rhs.it_range.end()) {}
+
         explicit expr(bool b) : m_type(TYPE_BOOL) { m_data.b = b; }
         explicit expr(bool b, const Iterator &it_begin, const Iterator &it_end) : m_type(TYPE_BOOL), it_range(it_begin, it_end) { m_data.b = b; }
         explicit expr(int i) : m_type(TYPE_INT) { m_data.i = i; }
@@ -201,11 +205,8 @@ namespace client
         explicit expr(const std::string &s) : m_type(TYPE_STRING) { m_data.s = new std::string(s); }
         explicit expr(const std::string &s, const Iterator &it_begin, const Iterator &it_end) : 
             m_type(TYPE_STRING), it_range(it_begin, it_end) { m_data.s = new std::string(s); }
-                 expr(const expr &rhs) : m_type(rhs.type()), it_range(rhs.it_range)
-            { if (rhs.type() == TYPE_STRING) m_data.s = new std::string(*rhs.m_data.s); else m_data.set(rhs.m_data); }
-        explicit expr(expr &&rhs) : expr(rhs, rhs.it_range.begin(), rhs.it_range.end()) {}
         explicit expr(expr &&rhs, const Iterator &it_begin, const Iterator &it_end) : m_type(rhs.type()), it_range{ it_begin, it_end }
-        {   
+        {
             m_data.set(rhs.m_data);
             rhs.m_type = TYPE_EMPTY;
         }
@@ -723,7 +724,10 @@ namespace client
         const DynamicConfig     *config                 = nullptr;
         const DynamicConfig     *config_override        = nullptr;
         mutable DynamicConfig   *config_outputs         = nullptr;
+        // Local variables, read / write
+        mutable DynamicConfig    config_local;
         size_t                   current_extruder_id    = 0;
+        // Random number generator and optionally global variables.
         PlaceholderParser::ContextData *context_data    = nullptr;
         // If false, the macro_processor will evaluate a full macro.
         // If true, the macro processor will evaluate just a boolean condition using the full expressive power of the macro processor.
@@ -748,7 +752,24 @@ namespace client
         }
 
         const ConfigOption*     resolve_symbol(const std::string &opt_key) const { return this->optptr(opt_key); }
-        ConfigOption*           resolve_output_symbol(const std::string &opt_key) const { return this->config_outputs ? this->config_outputs->optptr(opt_key, false) : nullptr; }
+        ConfigOption*           resolve_output_symbol(const std::string &opt_key) const { 
+            ConfigOption *out = nullptr;
+            if (this->config_outputs)
+                out = this->config_outputs->optptr(opt_key, false);
+            if (out == nullptr && this->context_data != nullptr && this->context_data->global_config)
+                out = this->context_data->global_config->optptr(opt_key);
+            if (out == nullptr)
+                out = this->config_local.optptr(opt_key);
+            return out;
+        }
+        void                    store_new_variable(const std::string &opt_key, ConfigOption *opt, bool global_variable) {
+            assert(opt != nullptr);
+            if (global_variable) {
+                assert(this->context_data != nullptr && this->context_data->global_config);
+                this->context_data->global_config->set_key_value(opt_key, opt);
+            } else
+                this->config_local.set_key_value(opt_key ,opt);
+        }
 
         template <typename Iterator>
         static void legacy_variable_expansion(
@@ -953,17 +974,101 @@ namespace client
             output.it_range = opt.it_range;
         }
 
-        // Decoding a scalar variable symbol "opt", assigning it a value of "param".
+        template<typename Iterator>
+        struct NewOldVariable {
+            std::string                      name;
+            boost::iterator_range<Iterator>  it_range;
+            ConfigOption                    *opt{ nullptr };
+        };
         template <typename Iterator>
-        static void variable_assign(
-            const MyContext                 *ctx,
-            OptWithPos<Iterator>            &opt,
-            expr<Iterator>                  &param,
-            // Not used, just clear it.
-            std::string                     &out)
+        static void new_old_variable(
+            const MyContext                         *ctx,
+            bool                                     global_variable,
+            const boost::iterator_range<Iterator>   &it_range,
+            NewOldVariable<Iterator>                &out)
         {
+            t_config_option_key key(std::string(it_range.begin(), it_range.end()));
+            if (const ConfigOption* opt = ctx->resolve_symbol(key); opt)
+                ctx->throw_exception("Symbol is already defined in read-only system dictionary", it_range);
+            if (ctx->config_outputs && ctx->config_outputs->optptr(key))
+                ctx->throw_exception("Symbol is already defined as system output variable", it_range);
+
+            bool has_global_dictionary = ctx->context_data != nullptr && ctx->context_data->global_config;
+            if (global_variable) {
+                if (! has_global_dictionary)
+                    ctx->throw_exception("Global variables are not available in this context", it_range);
+                if (ctx->config_local.optptr(key))
+                    ctx->throw_exception("Variable name already defined in local scope", it_range);
+                out.opt = ctx->context_data->global_config->optptr(key);
+            } else {
+                if (has_global_dictionary && ctx->context_data->global_config->optptr(key))
+                    ctx->throw_exception("Variable name already defined in global scope", it_range);
+                out.opt = ctx->config_local.optptr(key);
+            }
+
+            out.name     = std::move(key);
+            out.it_range = it_range;
+        }
+
+        template <typename Iterator>
+        static void new_scalar_variable(
+            const MyContext                         *ctx,
+            bool                                     global_variable,
+            NewOldVariable<Iterator>                &output_variable,
+            const expr<Iterator>                    &param)
+        {
+            auto check_numeric = [](const expr<Iterator> &param) {
+                if (! param.numeric_type())
+                    param.throw_exception("Right side is not a numeric expression");
+            };
+            if (output_variable.opt) {
+                if (output_variable.opt->is_vector())
+                    param.throw_exception("Cannot assign a scalar value to a vector variable.");
+                switch (output_variable.opt->type()) {
+                case coFloat:
+                    check_numeric(param);
+                    static_cast<ConfigOptionFloat*>(output_variable.opt)->value = param.as_d();
+                    break;
+                case coInt:
+                    check_numeric(param);
+                    static_cast<ConfigOptionInt*>(output_variable.opt)->value = param.as_i();
+                    break;
+                case coString:
+                    static_cast<ConfigOptionString*>(output_variable.opt)->value = param.to_string();
+                    break;
+                case coBool:
+                    if (param.type() != expr<Iterator>::TYPE_BOOL)
+                        param.throw_exception("Right side is not a boolean expression");
+                    static_cast<ConfigOptionBool*>(output_variable.opt)->value = param.b();
+                    break;
+                default: assert(false);
+                }
+            } else {
+                switch (param.type()) {
+                    case expr<Iterator>::TYPE_BOOL:     output_variable.opt = new ConfigOptionBool(param.b());   break;
+                    case expr<Iterator>::TYPE_INT:      output_variable.opt = new ConfigOptionInt(param.i());    break;
+                    case expr<Iterator>::TYPE_DOUBLE:   output_variable.opt = new ConfigOptionFloat(param.d());  break;
+                    case expr<Iterator>::TYPE_STRING:   output_variable.opt = new ConfigOptionString(param.s()); break;
+                    default: assert(false);
+                }
+                const_cast<MyContext*>(ctx)->store_new_variable(output_variable.name, output_variable.opt, global_variable);
+            }
+        }
+
+        template <typename Iterator>
+        static void check_writable(const MyContext *ctx, OptWithPos<Iterator> &opt) {
             if (! opt.writable)
                 ctx->throw_exception("Cannot modify a read-only variable", opt.it_range);
+        }
+
+        // Decoding a scalar variable symbol "opt", assigning it a value of "param".
+        template <typename Iterator>
+        static void assign_scalar_variable(
+            const MyContext                 *ctx,
+            OptWithPos<Iterator>            &opt,
+            expr<Iterator>                  &param)
+        {
+            check_writable(ctx, opt);
             auto check_numeric = [](const expr<Iterator> &param) {
                 if (! param.numeric_type())
                     param.throw_exception("Right side is not a numeric expression");
@@ -1028,7 +1133,363 @@ namespace client
                     ctx->throw_exception("Unsupported output scalar variable type", opt.it_range);
                 }
             }
-            out.clear();
+        }
+
+        template <typename Iterator>
+        static void new_vector_variable_array(
+            const MyContext                         *ctx,
+            bool                                     global_variable,
+            NewOldVariable<Iterator>                &output_variable,
+            const expr<Iterator>                    &expr_count,
+            const expr<Iterator>                    &expr_value)
+        {
+            auto check_numeric = [](const expr<Iterator> &param) {
+                if (! param.numeric_type())
+                    param.throw_exception("Right side is not a numeric expression");
+            };
+            auto evaluate_count = [](const expr<Iterator> &expr_count) -> size_t {
+                if (expr_count.type() != expr<Iterator>::TYPE_INT)
+                    expr_count.throw_exception("Expected number of elements to fill a vector with.");
+                int count = expr_count.i();
+                if (count < 0)
+                    expr_count.throw_exception("Negative number of elements specified.");
+                return size_t(count);
+            };
+            if (output_variable.opt) {
+                if (output_variable.opt->is_scalar())
+                    expr_value.throw_exception("Cannot assign a vector value to a scalar variable.");
+                size_t count = evaluate_count(expr_count);
+                switch (output_variable.opt->type()) {
+                case coFloats:
+                    check_numeric(expr_value);
+                    static_cast<ConfigOptionFloats*>(output_variable.opt)->values.assign(count, expr_value.as_d());
+                    break;
+                case coInts:
+                    check_numeric(expr_value);
+                    static_cast<ConfigOptionInts*>(output_variable.opt)->values.assign(count, expr_value.as_i());
+                    break;
+                case coStrings:
+                    static_cast<ConfigOptionStrings*>(output_variable.opt)->values.assign(count, expr_value.to_string());
+                    break;
+                case coBools:
+                    if (expr_value.type() != expr<Iterator>::TYPE_BOOL)
+                        expr_value.throw_exception("Right side is not a boolean expression");
+                    static_cast<ConfigOptionBools*>(output_variable.opt)->values.assign(count, expr_value.b());
+                    break;
+                default: assert(false);
+                }
+            } else {
+                size_t count = evaluate_count(expr_count);
+                switch (expr_value.type()) {
+                    case expr<Iterator>::TYPE_BOOL:     output_variable.opt = new ConfigOptionBools(count, expr_value.b());   break;
+                    case expr<Iterator>::TYPE_INT:      output_variable.opt = new ConfigOptionInts(count, expr_value.i());    break;
+                    case expr<Iterator>::TYPE_DOUBLE:   output_variable.opt = new ConfigOptionFloats(count, expr_value.d()); break;
+                    case expr<Iterator>::TYPE_STRING:   output_variable.opt = new ConfigOptionStrings(count, expr_value.s()); break;
+                    default: assert(false);
+                }
+                const_cast<MyContext*>(ctx)->store_new_variable(output_variable.name, output_variable.opt, global_variable);
+            }
+        }
+
+        template <typename Iterator>
+        static void assign_vector_variable_array(
+            const MyContext                         *ctx,
+            OptWithPos<Iterator>                    &lhs,
+            const expr<Iterator>                    &expr_count,
+            const expr<Iterator>                    &expr_value)
+        {
+            check_writable(ctx, lhs);
+            auto check_numeric = [](const expr<Iterator> &param) {
+                if (! param.numeric_type())
+                    param.throw_exception("Right side is not a numeric expression");
+            };
+            auto evaluate_count = [](const expr<Iterator> &expr_count) -> size_t {
+                if (expr_count.type() != expr<Iterator>::TYPE_INT)
+                    expr_count.throw_exception("Expected number of elements to fill a vector with.");
+                int count = expr_count.i();
+                if (count < 0)
+                    expr_count.throw_exception("Negative number of elements specified.");
+                return size_t(count);
+            };
+            if (lhs.opt->is_scalar())
+                expr_value.throw_exception("Cannot assign a vector value to a scalar variable.");
+            auto *opt = const_cast<ConfigOption*>(lhs.opt);
+            size_t count = evaluate_count(expr_count);
+            switch (lhs.opt->type()) {
+            case coFloats:
+                check_numeric(expr_value);
+                static_cast<ConfigOptionFloats*>(opt)->values.assign(count, expr_value.as_d());
+                break;
+            case coInts:
+                check_numeric(expr_value);
+                static_cast<ConfigOptionInts*>(opt)->values.assign(count, expr_value.as_i());
+                break;
+            case coStrings:
+                static_cast<ConfigOptionStrings*>(opt)->values.assign(count, expr_value.to_string());
+                break;
+            case coBools:
+                if (expr_value.type() != expr<Iterator>::TYPE_BOOL)
+                    expr_value.throw_exception("Right side is not a boolean expression");
+                static_cast<ConfigOptionBools*>(opt)->values.assign(count, expr_value.b());
+                break;
+            default: assert(false);
+            }
+        }
+
+        template <typename Iterator>
+        static void new_vector_variable_initializer_list(
+            const MyContext                             *ctx,
+            bool                                         global_variable,
+            NewOldVariable<Iterator>                    &output_variable,
+            const std::vector<expr<Iterator>>           &il)
+        {
+            if (! output_variable.opt) {
+                // First guesstimate type of the output vector.
+                size_t num_bool = 0;
+                size_t num_int = 0;
+                size_t num_double = 0;
+                size_t num_string = 0;
+                for (auto &i : il)
+                    switch (i.type()) {
+                    case expr<Iterator>::TYPE_BOOL:     ++ num_bool;    break;
+                    case expr<Iterator>::TYPE_INT:      ++ num_int;     break;
+                    case expr<Iterator>::TYPE_DOUBLE:   ++ num_double;  break;
+                    case expr<Iterator>::TYPE_STRING:   ++ num_string;  break;
+                    default: assert(false);
+                    }
+                if (num_string > 0)
+                    // Convert everything to strings.
+                    output_variable.opt = new ConfigOptionStrings();
+                else if (num_bool > 0) {
+                    if (num_double + num_int > 0)
+                        ctx->throw_exception("Right side is not valid: Mixing numeric and boolean types.", boost::iterator_range<Iterator>{ il.front().it_range.begin(), il.back().it_range.end() });
+                    output_variable.opt = new ConfigOptionBools();
+                } else
+                    // Output is numeric.
+                    output_variable.opt = num_double == 0 ? static_cast<ConfigOption*>(new ConfigOptionInts()) : static_cast<ConfigOption*>(new ConfigOptionFloats());
+                const_cast<MyContext*>(ctx)->store_new_variable(output_variable.name, output_variable.opt, global_variable);
+            }
+
+            auto check_numeric = [](const std::vector<expr<Iterator>> &il) {
+                for (auto& i : il)
+                    if (!i.numeric_type())
+                        i.throw_exception("Right side is not a numeric expression");
+            };
+
+            if (output_variable.opt->is_scalar())
+                ctx->throw_exception("Cannot assign a vector value to a scalar variable.", output_variable.it_range);
+
+            switch (output_variable.opt->type()) {
+            case coFloats:
+            {
+                check_numeric(il);
+                auto &out = static_cast<ConfigOptionFloats*>(output_variable.opt)->values;
+                out.clear();
+                out.reserve(il.size());
+                for (auto &i : il)
+                    out.emplace_back(i.as_d());
+                break;
+            }
+            case coInts:
+            {
+                check_numeric(il);
+                auto &out = static_cast<ConfigOptionInts*>(output_variable.opt)->values;
+                out.clear();
+                out.reserve(il.size());
+                for (auto& i : il)
+                    out.emplace_back(i.as_i());
+                break;
+            }
+            case coStrings:
+            {
+                auto &out = static_cast<ConfigOptionStrings*>(output_variable.opt)->values;
+                out.clear();
+                out.reserve(il.size());
+                for (auto &i : il)
+                    out.emplace_back(i.to_string());
+                break;
+            }
+            case coBools:
+            {
+                auto &out = static_cast<ConfigOptionBools*>(output_variable.opt)->values;
+                out.clear();
+                out.reserve(il.size());
+                for (auto &i : il)
+                    if (i.type() == expr<Iterator>::TYPE_BOOL)
+                        out.emplace_back(i.b());
+                    else
+                        i.throw_exception("Right side is not a boolean expression");
+                break;
+            }
+            default:
+                assert(false);
+            }
+        }
+
+        template <typename Iterator>
+        static void assign_vector_variable_initializer_list(
+            const MyContext                             *ctx,
+            OptWithPos<Iterator>                        &lhs,
+            const std::vector<expr<Iterator>>           &il)
+        {
+            check_writable(ctx, lhs);
+            auto check_numeric = [](const std::vector<expr<Iterator>> &il) {
+                for (auto &i : il)
+                    if (! i.numeric_type())
+                        i.throw_exception("Right side is not a numeric expression");
+            };
+
+            if (lhs.opt->is_scalar())
+                ctx->throw_exception("Cannot assign a vector value to a scalar variable.", lhs.it_range);
+
+            ConfigOption *opt = const_cast<ConfigOption*>(lhs.opt);
+            switch (lhs.opt->type()) {
+            case coFloats:
+            {
+                check_numeric(il);
+                auto &out = static_cast<ConfigOptionFloats*>(opt)->values;
+                out.clear();
+                out.reserve(il.size());
+                for (auto &i : il)
+                    out.emplace_back(i.as_d());
+                break;
+            }
+            case coInts:
+            {
+                check_numeric(il);
+                auto &out = static_cast<ConfigOptionInts*>(opt)->values;
+                out.clear();
+                out.reserve(il.size());
+                for (auto& i : il)
+                    out.emplace_back(i.as_i());
+                break;
+            }
+            case coStrings:
+            {
+                auto &out = static_cast<ConfigOptionStrings*>(opt)->values;
+                out.clear();
+                out.reserve(il.size());
+                for (auto &i : il)
+                    out.emplace_back(i.to_string());
+                break;
+            }
+            case coBools:
+            {
+                auto &out = static_cast<ConfigOptionBools*>(opt)->values;
+                out.clear();
+                out.reserve(il.size());
+                for (auto &i : il)
+                    if (i.type() == expr<Iterator>::TYPE_BOOL)
+                        out.emplace_back(i.b());
+                    else
+                        i.throw_exception("Right side is not a boolean expression");
+                break;
+            }
+            default:
+                assert(false);
+            }
+        }
+
+        template <typename Iterator>
+        static bool new_vector_variable_copy(
+            const MyContext                             *ctx,
+            bool                                         global_variable,
+            NewOldVariable<Iterator>                    &output_variable,
+            const OptWithPos<Iterator>                  &src_variable)
+        {
+            if (! is_vector_variable_reference(src_variable))
+                // Skip parsing this branch, bactrack.
+                return false;
+
+            if (! output_variable.opt) {
+                if (one_of(src_variable.opt->type(), { coFloats, coInts, coStrings, coBools }))
+                    output_variable.opt = src_variable.opt->clone();
+                else if (src_variable.opt->type() == coPercents)
+                    output_variable.opt = new ConfigOptionFloats(static_cast<const ConfigOptionPercents*>(src_variable.opt)->values);
+                else
+                    ctx->throw_exception("Duplicating this vector variable is not supported", src_variable.it_range);
+                const_cast<MyContext*>(ctx)->store_new_variable(output_variable.name, output_variable.opt, global_variable);
+            }
+
+            switch (output_variable.opt->type()) {
+            case coFloats:
+                if (output_variable.opt->type() != coFloats)
+                    ctx->throw_exception("Left hand side is a float vector, while the right hand side is not.", boost::iterator_range<Iterator>{ output_variable.it_range.begin(), src_variable.it_range.end() });
+                static_cast<ConfigOptionFloats*>(output_variable.opt)->values = static_cast<const ConfigOptionFloats*>(src_variable.opt)->values;
+                break;
+            case coInts:
+                if (output_variable.opt->type() != coInts)
+                    ctx->throw_exception("Left hand side is an int vector, while the right hand side is not.", boost::iterator_range<Iterator>{ output_variable.it_range.begin(), src_variable.it_range.end() });
+                static_cast<ConfigOptionInts*>(output_variable.opt)->values = static_cast<const ConfigOptionInts*>(src_variable.opt)->values;
+                break;
+            case coStrings:
+                if (output_variable.opt->type() != coStrings)
+                    ctx->throw_exception("Left hand side is a string vector, while the right hand side is not.", boost::iterator_range<Iterator>{ output_variable.it_range.begin(), src_variable.it_range.end() });
+                static_cast<ConfigOptionStrings*>(output_variable.opt)->values = static_cast<const ConfigOptionStrings*>(src_variable.opt)->values;
+                break;
+            case coBools:
+                if (output_variable.opt->type() != coBools)
+                    ctx->throw_exception("Left hand side is a bool vector, while the right hand side is not.", boost::iterator_range<Iterator>{ output_variable.it_range.begin(), src_variable.it_range.end() });
+                static_cast<ConfigOptionBools*>(output_variable.opt)->values = static_cast<const ConfigOptionBools*>(src_variable.opt)->values;
+                break;
+            default:
+                assert(false);
+            }
+            // Continue parsing.
+            return true;
+        }
+
+        template <typename Iterator>
+        static bool is_vector_variable_reference(const OptWithPos<Iterator> &var) {
+            return ! var.has_index() && var.opt->is_vector();
+        }
+
+        template <typename Iterator>
+        static bool assign_vector_variable_copy(
+            const MyContext                             *ctx,
+            OptWithPos<Iterator>                        &lhs,
+            const OptWithPos<Iterator>                  &src_variable)
+        {
+            if (! is_vector_variable_reference(src_variable))
+                // Skip parsing this branch, bactrack.
+                return false;
+
+            check_writable(ctx, lhs);
+
+            auto *opt = const_cast<ConfigOption*>(lhs.opt);
+            switch (lhs.opt->type()) {
+            case coFloats:
+                if (lhs.opt->type() != coFloats)
+                    ctx->throw_exception("Left hand side is a float vector, while the right hand side is not.", lhs.it_range);
+                static_cast<ConfigOptionFloats*>(opt)->values = static_cast<const ConfigOptionFloats*>(src_variable.opt)->values;
+                break;
+            case coInts:
+                if (lhs.opt->type() != coInts)
+                    ctx->throw_exception("Left hand side is an int vector, while the right hand side is not.", lhs.it_range);
+                static_cast<ConfigOptionInts*>(opt)->values = static_cast<const ConfigOptionInts*>(src_variable.opt)->values;
+                break;
+            case coStrings:
+                if (lhs.opt->type() != coStrings)
+                    ctx->throw_exception("Left hand side is a string vector, while the right hand side is not.", lhs.it_range);
+                static_cast<ConfigOptionStrings*>(opt)->values = static_cast<const ConfigOptionStrings*>(src_variable.opt)->values;
+                break;
+            case coBools:
+                if (lhs.opt->type() != coBools)
+                    ctx->throw_exception("Left hand side is a bool vector, while the right hand side is not.", lhs.it_range);
+                static_cast<ConfigOptionBools*>(opt)->values = static_cast<const ConfigOptionBools*>(src_variable.opt)->values;
+                break;
+            default:
+                assert(false);
+            }
+
+            // Continue parsing.
+            return true;
+        }
+
+        template <typename Iterator>
+        static void new_vector_variable_initializer_list_append(std::vector<expr<Iterator>> &list, expr<Iterator> &expr)
+        {
+            list.emplace_back(std::move(expr));
         }
 
         // Verify that the expression returns an integer, which may be used
@@ -1175,6 +1636,7 @@ namespace client
 
     // Table to translate symbol tag to a human readable error message.
     std::map<std::string, std::string> MyContext::tag_to_error_message = {
+        { "array",                      "Unknown syntax error" },
         { "eoi",                        "Unknown syntax error" },
         { "start",                      "Unknown syntax error" },
         { "text",                       "Invalid text." },
@@ -1335,7 +1797,7 @@ namespace client
                         // Allow back tracking after '{' in case of a text_block embedded inside a condition.
                         // In that case the inner-most {else} wins and the {if}/{elsif}/{else} shall be paired.
                         // {elsif}/{else} without an {if} will be allowed to back track from the embedded text_block.
-                    |   (lit('{') >> macro(_r1) [_val+=_1] > '}')
+                    |   (lit('{') >> macro(_r1)[_val+=_1] > *(+lit(';') >> macro(_r1)[_val+=_1]) > *lit(';') > '}')
                     |   (lit('[') > legacy_variable_expansion(_r1) [_val+=_1] > ']')
                 );
             text_block.name("text_block");
@@ -1351,6 +1813,7 @@ namespace client
                     (kw["if"]     > if_else_output(_r1) [_val = _1])
 //                |   (kw["switch"] > switch_output(_r1)  [_val = _1])
                   |   (assignment_statement(_r1) [_val = _1])
+                  |   (new_variable_statement(_r1) [_val = _1])
                   |   (additive_expression(_r1) [ px::bind(&expr<Iterator>::to_string2, _1, _val) ])
                 ;
             macro.name("macro");
@@ -1445,8 +1908,39 @@ namespace client
             multiplicative_expression.name("multiplicative_expression");
 
             assignment_statement =
-                (variable_reference(_r1) >> '=' > additive_expression(_r1))
-                    [px::bind(&MyContext::variable_assign<Iterator>, _r1, _1, _2, _val)];
+                variable_reference(_r1)[_a = _1] >> '=' > 
+                (       // Consumes also '(' conditional_expression ')', that means enclosing an expression into braces makes it a single value vector initializer.
+                        (lit('(') > new_variable_initializer_list(_r1) > ')') 
+                            [px::bind(&MyContext::assign_vector_variable_initializer_list<Iterator>, _r1, _a, _1)]
+                        // Process it before conditional_expression, as conditional_expression requires a vector reference to be augmented with an index.
+                        // Only process such variable references, which return a naked vector variable.
+                    |  variable_reference(_r1)
+                            [px::ref(qi::_pass) = px::bind(&MyContext::assign_vector_variable_copy<Iterator>, _r1, _a, _1)]
+                       // Would NOT consume '(' conditional_expression ')' because such value was consumed with the expression above.
+                    |  conditional_expression(_r1)
+                            [px::bind(&MyContext::assign_scalar_variable<Iterator>, _r1, _a, _1)]
+                    |  (kw["array"] > "(" > additive_expression(_r1) > "," > conditional_expression(_r1) > ")")
+                            [px::bind(&MyContext::assign_vector_variable_array<Iterator>, _r1, _a, _1, _2)]
+                );
+  
+            new_variable_statement =
+                (kw["local"][_a = false] | kw["global"][_a = true]) > identifier[px::bind(&MyContext::new_old_variable<Iterator>, _r1, _a, _1, _b)] > lit('=') >
+                (       // Consumes also '(' conditional_expression ')', that means enclosing an expression into braces makes it a single value vector initializer.
+                        (lit('(') > new_variable_initializer_list(_r1) > ')') 
+                            [px::bind(&MyContext::new_vector_variable_initializer_list<Iterator>, _r1, _a, _b, _1)]
+                        // Process it before conditional_expression, as conditional_expression requires a vector reference to be augmented with an index.
+                        // Only process such variable references, which return a naked vector variable.
+                    |  variable_reference(_r1)
+                            [px::ref(qi::_pass) = px::bind(&MyContext::new_vector_variable_copy<Iterator>, _r1, _a, _b, _1)]
+                       // Would NOT consume '(' conditional_expression ')' because such value was consumed with the expression above.
+                    |  conditional_expression(_r1)
+                            [px::bind(&MyContext::new_scalar_variable<Iterator>, _r1, _a, _b, _1)]
+                    |  (kw["array"] > "(" > additive_expression(_r1) > "," > conditional_expression(_r1) > ")")
+                            [px::bind(&MyContext::new_vector_variable_array<Iterator>, _r1, _a, _b, _1, _2)]
+                );
+            new_variable_initializer_list = 
+                             conditional_expression(_r1)[px::bind(&MyContext::new_vector_variable_initializer_list_append<Iterator>, _val, _1)] >>
+                *(lit(',') > conditional_expression(_r1)[px::bind(&MyContext::new_vector_variable_initializer_list_append<Iterator>, _val, _1)]);
 
             struct FactorActions {
                 static void set_start_pos(Iterator &start_pos, expr<Iterator> &out)
@@ -1544,23 +2038,26 @@ namespace client
             variable_reference.name("variable reference");
 
             variable = identifier[ px::bind(&MyContext::resolve_variable<Iterator>, _r1, _1, _val) ];
-            variable.name("variable reference");
+            variable.name("variable name");
 
             regular_expression = raw[lexeme['/' > *((utf8char - char_('\\') - char_('/')) | ('\\' > char_)) > '/']];
             regular_expression.name("regular_expression");
 
             keywords.add
                 ("and")
+                ("array")
                 ("digits")
                 ("zdigits")
                 ("if")
                 ("int")
                 ("is_nil")
+                ("local")
                 //("inf")
                 ("else")
                 ("elsif")
                 ("endif")
                 ("false")
+                ("global")
                 ("interpolate_table")
                 ("min")
                 ("max")
@@ -1653,9 +2150,12 @@ namespace client
         qi::rule<Iterator, InterpolateTableContext<Iterator>(const MyContext*, const expr<Iterator> &param), spirit_encoding::space_type> interpolate_table_list;
 
         qi::rule<Iterator, std::string(const MyContext*), qi::locals<bool, bool>, spirit_encoding::space_type> if_else_output;
-        qi::rule<Iterator, std::string(const MyContext*), qi::locals<OptWithPos<Iterator>, int>, spirit_encoding::space_type> assignment_statement;
-//        qi::rule<Iterator, std::string(const MyContext*), qi::locals<expr<Iterator>, bool, std::string>, spirit_encoding::space_type> switch_output;
+        qi::rule<Iterator, std::string(const MyContext*), qi::locals<OptWithPos<Iterator>>, spirit_encoding::space_type> assignment_statement;
+        // Allocating new local or global variables.
+        qi::rule<Iterator, std::string(const MyContext*), qi::locals<bool, MyContext::NewOldVariable<Iterator>>, spirit_encoding::space_type> new_variable_statement;
+        qi::rule<Iterator, std::vector<expr<Iterator>>(const MyContext*), spirit_encoding::space_type> new_variable_initializer_list;
 
+//        qi::rule<Iterator, std::string(const MyContext*), qi::locals<expr<Iterator>, bool, std::string>, spirit_encoding::space_type> switch_output;
         qi::symbols<char> keywords;
     };
 }

src/libslic3r/PlaceholderParser.hpp

@@ -20,7 +20,10 @@ public:
     // In the future, the context may hold variables created and modified by the PlaceholderParser
     // and shared between the PlaceholderParser::process() invocations.
     struct ContextData {
-        std::mt19937 rng;
+        std::mt19937                    rng;
+        // If defined, then this dictionary is used by the scripts to define user variables and persist them
+        // between PlaceholderParser evaluations.
+        std::unique_ptr<DynamicConfig>  global_config;
     };
 
     PlaceholderParser(const DynamicConfig *external_config = nullptr);

tests/libslic3r/test_placeholder_parser.cpp

@@ -39,6 +39,10 @@ SCENARIO("Placeholder parser scripting", "[PlaceholderParser]") {
     SECTION("nullable is not null") { REQUIRE(parser.process("{is_nil(filament_retract_length[0])}") == "false"); }
     SECTION("nullable is null") { REQUIRE(parser.process("{is_nil(filament_retract_length[1])}") == "true"); }
     SECTION("nullable is not null 2") { REQUIRE(parser.process("{is_nil(filament_retract_length[2])}") == "false"); }
+    SECTION("multiple expressions") { REQUIRE(parser.process("{temperature[foo];temperature[foo]}") == "357357"); }
+    SECTION("multiple expressions with semicolons") { REQUIRE(parser.process("{temperature[foo];;;temperature[foo];}") == "357357"); }
+    SECTION("multiple expressions with semicolons 2") { REQUIRE(parser.process("{temperature[foo];;temperature[foo];}") == "357357"); }
+    SECTION("multiple expressions with semicolons 3") { REQUIRE(parser.process("{temperature[foo];;;temperature[foo];;}") == "357357"); }
 
     // Test the math expressions.
     SECTION("math: 2*3") { REQUIRE(parser.process("{2*3}") == "6"); }
@@ -146,3 +150,76 @@ SCENARIO("Placeholder parser scripting", "[PlaceholderParser]") {
         REQUIRE(config_outputs.opt_float("writable_floats", 1) == Approx(33.));
     }
 }
+
+SCENARIO("Placeholder parser variables", "[PlaceholderParser]") {
+    PlaceholderParser 	parser;
+    auto 				config = DynamicPrintConfig::full_print_config();
+
+    config.set_deserialize_strict({
+        { "filament_notes", "testnotes" },
+        { "enable_dynamic_fan_speeds", "1" },
+        { "nozzle_diameter", "0.6;0.6;0.6;0.6" },
+        { "temperature", "357;359;363;378" }
+        });
+
+    PlaceholderParser::ContextData context_with_global_dict;
+    context_with_global_dict.global_config = std::make_unique<DynamicConfig>();
+
+    SECTION("create an int local variable") { REQUIRE(parser.process("{local myint = 33+2}{myint}", 0, nullptr, nullptr, nullptr) == "35"); }
+    SECTION("create a string local variable") { REQUIRE(parser.process("{local mystr = \"mine\" + \"only\" + \"mine\"}{mystr}", 0, nullptr, nullptr, nullptr) == "mineonlymine"); }
+    SECTION("create a bool local variable") { REQUIRE(parser.process("{local mybool = 1 + 1 == 2}{mybool}", 0, nullptr, nullptr, nullptr) == "true"); }
+    SECTION("create an int global variable") { REQUIRE(parser.process("{global myint = 33+2}{myint}", 0, nullptr, nullptr, &context_with_global_dict) == "35"); }
+    SECTION("create a string global variable") { REQUIRE(parser.process("{global mystr = \"mine\" + \"only\" + \"mine\"}{mystr}", 0, nullptr, nullptr, &context_with_global_dict) == "mineonlymine"); }
+    SECTION("create a bool global variable") { REQUIRE(parser.process("{global mybool = 1 + 1 == 2}{mybool}", 0, nullptr, nullptr, &context_with_global_dict) == "true"); }
+
+    SECTION("create an int local variable and overwrite it") { REQUIRE(parser.process("{local myint = 33+2}{myint = 12}{myint}", 0, nullptr, nullptr, nullptr) == "12"); }
+    SECTION("create a string local variable and overwrite it") { REQUIRE(parser.process("{local mystr = \"mine\" + \"only\" + \"mine\"}{mystr = \"yours\"}{mystr}", 0, nullptr, nullptr, nullptr) == "yours"); }
+    SECTION("create a bool local variable and overwrite it") { REQUIRE(parser.process("{local mybool = 1 + 1 == 2}{mybool = false}{mybool}", 0, nullptr, nullptr, nullptr) == "false"); }
+    SECTION("create an int global variable and overwrite it") { REQUIRE(parser.process("{global myint = 33+2}{myint = 12}{myint}", 0, nullptr, nullptr, &context_with_global_dict) == "12"); }
+    SECTION("create a string global variable and overwrite it") { REQUIRE(parser.process("{global mystr = \"mine\" + \"only\" + \"mine\"}{mystr = \"yours\"}{mystr}", 0, nullptr, nullptr, &context_with_global_dict) == "yours"); }
+    SECTION("create a bool global variable and overwrite it") { REQUIRE(parser.process("{global mybool = 1 + 1 == 2}{mybool = false}{mybool}", 0, nullptr, nullptr, &context_with_global_dict) == "false"); }
+
+    SECTION("create an int local variable and redefine it") { REQUIRE(parser.process("{local myint = 33+2}{local myint = 12}{myint}", 0, nullptr, nullptr, nullptr) == "12"); }
+    SECTION("create a string local variable and redefine it") { REQUIRE(parser.process("{local mystr = \"mine\" + \"only\" + \"mine\"}{local mystr = \"yours\"}{mystr}", 0, nullptr, nullptr, nullptr) == "yours"); }
+    SECTION("create a bool local variable and redefine it") { REQUIRE(parser.process("{local mybool = 1 + 1 == 2}{local mybool = false}{mybool}", 0, nullptr, nullptr, nullptr) == "false"); }
+    SECTION("create an int global variable and redefine it") { REQUIRE(parser.process("{global myint = 33+2}{global myint = 12}{myint}", 0, nullptr, nullptr, &context_with_global_dict) == "12"); }
+    SECTION("create a string global variable and redefine it") { REQUIRE(parser.process("{global mystr = \"mine\" + \"only\" + \"mine\"}{global mystr = \"yours\"}{mystr}", 0, nullptr, nullptr, &context_with_global_dict) == "yours"); }
+    SECTION("create a bool global variable and redefine it") { REQUIRE(parser.process("{global mybool = 1 + 1 == 2}{global mybool = false}{mybool}", 0, nullptr, nullptr, &context_with_global_dict) == "false"); }
+
+    SECTION("create an ints local variable with array()") { REQUIRE(parser.process("{local myint = array(2*3, 4*6)}{myint[5]}", 0, nullptr, nullptr, nullptr) == "24"); }
+    SECTION("create a strings local variable array()") { REQUIRE(parser.process("{local mystr = array(2*3, \"mine\" + \"only\" + \"mine\")}{mystr[5]}", 0, nullptr, nullptr, nullptr) == "mineonlymine"); }
+    SECTION("create a bools local variable array()") { REQUIRE(parser.process("{local mybool = array(5, 1 + 1 == 2)}{mybool[4]}", 0, nullptr, nullptr, nullptr) == "true"); }
+    SECTION("create an ints global variable array()") { REQUIRE(parser.process("{global myint = array(2*3, 4*6)}{myint[5]}", 0, nullptr, nullptr, &context_with_global_dict) == "24"); }
+    SECTION("create a strings global variable array()") { REQUIRE(parser.process("{global mystr = array(2*3, \"mine\" + \"only\" + \"mine\")}{mystr[5]}", 0, nullptr, nullptr, &context_with_global_dict) == "mineonlymine"); }
+    SECTION("create a bools global variable array()") { REQUIRE(parser.process("{global mybool = array(5, 1 + 1 == 2)}{mybool[4]}", 0, nullptr, nullptr, &context_with_global_dict) == "true"); }
+
+    SECTION("create an ints local variable with initializer list") { REQUIRE(parser.process("{local myint = (2*3, 4*6, 5*5)}{myint[1]}", 0, nullptr, nullptr, nullptr) == "24"); }
+    SECTION("create a strings local variable with initializer list") { REQUIRE(parser.process("{local mystr = (2*3, \"mine\" + \"only\" + \"mine\", 8)}{mystr[1]}", 0, nullptr, nullptr, nullptr) == "mineonlymine"); }
+    SECTION("create a bools local variable with initializer list") { REQUIRE(parser.process("{local mybool = (3*3 == 8, 1 + 1 == 2)}{mybool[1]}", 0, nullptr, nullptr, nullptr) == "true"); }
+    SECTION("create an ints global variable with initializer list") { REQUIRE(parser.process("{global myint = (2*3, 4*6, 5*5)}{myint[1]}", 0, nullptr, nullptr, &context_with_global_dict) == "24"); }
+    SECTION("create a strings global variable with initializer list") { REQUIRE(parser.process("{global mystr = (2*3, \"mine\" + \"only\" + \"mine\", 8)}{mystr[1]}", 0, nullptr, nullptr, &context_with_global_dict) == "mineonlymine"); }
+    SECTION("create a bools global variable with initializer list") { REQUIRE(parser.process("{global mybool = (2*3 == 8, 1 + 1 == 2, 5*5 != 33)}{mybool[1]}", 0, nullptr, nullptr, &context_with_global_dict) == "true"); }
+
+    SECTION("create an ints local variable by a copy") { REQUIRE(parser.process("{local myint = temperature}{myint[0]}", 0, &config, nullptr, nullptr) == "357"); }
+    SECTION("create a strings local variable by a copy") { REQUIRE(parser.process("{local mystr = filament_notes}{mystr[0]}", 0, &config, nullptr, nullptr) == "testnotes"); }
+    SECTION("create a bools local variable by a copy") { REQUIRE(parser.process("{local mybool = enable_dynamic_fan_speeds}{mybool[0]}", 0, &config, nullptr, nullptr) == "true"); }
+    SECTION("create an ints global variable by a copy") { REQUIRE(parser.process("{global myint = temperature}{myint[0]}", 0, &config, nullptr, &context_with_global_dict) == "357"); }
+    SECTION("create a strings global variable by a copy") { REQUIRE(parser.process("{global mystr = filament_notes}{mystr[0]}", 0, &config, nullptr, &context_with_global_dict) == "testnotes"); }
+    SECTION("create a bools global variable by a copy") { REQUIRE(parser.process("{global mybool = enable_dynamic_fan_speeds}{mybool[0]}", 0, &config, nullptr, &context_with_global_dict) == "true"); }
+
+    SECTION("create an ints local variable by a copy and overwrite it") {
+        REQUIRE(parser.process("{local myint = temperature}{myint = array(2*3, 4*6)}{myint[5]}", 0, &config, nullptr, nullptr) == "24");
+        REQUIRE(parser.process("{local myint = temperature}{myint = (2*3, 4*6)}{myint[1]}", 0, &config, nullptr, nullptr) == "24");
+        REQUIRE(parser.process("{local myint = temperature}{myint = (1)}{myint = temperature}{myint[0]}", 0, &config, nullptr, nullptr) == "357");
+    }
+    SECTION("create a strings local variable by a copy and overwrite it") {
+        REQUIRE(parser.process("{local mystr = filament_notes}{mystr = array(2*3, \"mine\" + \"only\" + \"mine\")}{mystr[5]}", 0, &config, nullptr, nullptr) == "mineonlymine");
+        REQUIRE(parser.process("{local mystr = filament_notes}{mystr = (2*3, \"mine\" + \"only\" + \"mine\")}{mystr[1]}", 0, &config, nullptr, nullptr) == "mineonlymine");
+        REQUIRE(parser.process("{local mystr = filament_notes}{mystr = (2*3, \"mine\" + \"only\" + \"mine\")}{mystr = filament_notes}{mystr[0]}", 0, &config, nullptr, nullptr) == "testnotes");
+    }
+    SECTION("create a bools local variable by a copy and overwrite it") {
+        REQUIRE(parser.process("{local mybool = enable_dynamic_fan_speeds}{mybool = array(2*3, true)}{mybool[5]}", 0, &config, nullptr, nullptr) == "true");
+        REQUIRE(parser.process("{local mybool = enable_dynamic_fan_speeds}{mybool = (false, true)}{mybool[1]}", 0, &config, nullptr, nullptr) == "true");
+        REQUIRE(parser.process("{local mybool = enable_dynamic_fan_speeds}{mybool = (false, false)}{mybool = enable_dynamic_fan_speeds}{mybool[0]}", 0, &config, nullptr, nullptr) == "true");
+    }
+}