modified coxeter notation parsing

CMakeLists.txt

@@ -12,6 +12,7 @@ include(External/glfw.cmake)
 include(External/gtest.cmake)
 include(External/imgui.cmake)
 include(External/json.cmake)
+include(External/peglib.cmake)
 
 include_directories(include)
 

External/peglib.cmake

@@ -0,0 +1,16 @@
+FetchContent_Declare(
+    peglib
+    GIT_REPOSITORY https://github.com/yhirose/cpp-peglib
+    GIT_TAG v1.8.2
+    GIT_PROGRESS TRUE
+)
+set(PEGLIB_BUILD_TESTS OFF CACHE INTERNAL "")
+FetchContent_GetProperties(peglib)
+if(NOT ${peglib}_POPULATED)
+    FetchContent_Populate(peglib)
+    find_package(Threads)
+    add_library(peglib INTERFACE ${peglib_SOURCE_DIR}/peglib.h)
+    target_include_directories(peglib INTERFACE ${peglib_SOURCE_DIR})
+    target_link_libraries(peglib INTERFACE Threads::Threads)
+    add_library(peglib::peglib ALIAS peglib)
+endif()

tc/CMakeLists.txt

@@ -1,14 +1,25 @@
 add_library(tc
-    include/tc/pair_map.hpp
     include/tc/core.hpp
     include/tc/cosets.hpp
     include/tc/group.hpp
     include/tc/groups.hpp
+    include/tc/lang.hpp
+    include/tc/pair_map.hpp
     include/tc/util.hpp
     src/core.cpp
-    src/groups.cpp)
-
+    src/groups.cpp
+    src/lang.cpp
+    )
+target_link_libraries(tc PUBLIC peglib::peglib fmt::fmt)
 target_include_directories(tc PUBLIC include)
 
+add_library(tc::tc ALIAS tc)
+
 add_subdirectory(test)
 add_subdirectory(bench)
+
+add_executable(langtest src/langtest.cpp)
+target_link_libraries(langtest PUBLIC tc::tc)
+
+add_executable(pegtest src/pegtest.cpp)
+target_link_libraries(pegtest PUBLIC peglib::peglib fmt::fmt)

tc/bench/benchmark.cpp

@@ -8,14 +8,14 @@
 #include <tc/core.hpp>
 #include <tc/groups.hpp>
 
-#define NAMED(x) #x, x
-
 void bench(
-    std::string group_expr,
-    const tc::Group &group,
+    const std::string &group_expr,
+    const std::string &symbol,
     const std::vector<tc::Gen> &gens,
     const tc::Coset bound = tc::UNBOUNDED
 ) {
+    tc::Group group = tc::coxeter(symbol);
+    
     std::clock_t s = std::clock();
     tc::Cosets cosets = tc::solve(group, gens, bound);
     std::clock_t e = std::clock();
@@ -43,29 +43,27 @@ tc::Group sch(T ...arg) {
 int main(int argc, char *argv[]) {
     std::vector<std::string> args(argv + 1, argv + argc);
 
-    using namespace tc::group;
-
     fmt::print("{:>24},{:>10},{:>6},{:>9},{:>10}\n", "NAME", "ORDER", "COMPL", "TIME", "COS/S");
 
-    bench(NAMED(H(2)), {});
-    bench(NAMED(H(3)), {});
-    bench(NAMED(H(4)), {});
+    bench("H2", "5", {});
+    bench("H3", "5 3", {});
+    bench("H4", "5 3 3", {});
     
-    bench(NAMED(T(100)), {});
-    bench(NAMED(T(500)), {});
-    bench(NAMED(T(1000)), {});
+    bench("T100", "100 2 100", {});
+    bench("T500", "500 2 500", {});
+    bench("T1000", "1000 2 1000", {});
 
-    bench(NAMED(E(6)), {});
-    bench(NAMED(E(7)), {});
+    bench("E6", "3 * [2 2 1]", {});
+    bench("E7", "3 * [3 2 1]", {});
+//    bench("E8", "3 * [4 2 1]", {});  // too big
 
-    bench(NAMED(B(6)), {});
-    bench(NAMED(B(7)), {});
-    bench(NAMED(B(8)), {});
+    bench("B6", "4 3 * 4", {});
+    bench("B7", "4 3 * 5", {});
+    bench("B8", "4 3 * 6", {});
 
-    auto g = tc::group::A(4);
-    g.set(tc::Rel{0, 3, 3});
-    bench("~A(3)", g, {}, 4385964);
-    bench("~I(1)", sch(tc::FREE), {}, 4385964);
+    bench("~A3", "{3 * 4}", {}, 5000000);
+    bench("~A4", "{3 * 5}", {}, 5000000);
+    bench("~I1", "{- * 5}", {}, 5000000);
 
     return EXIT_SUCCESS;
 }

tc/include/tc/core.hpp

@@ -10,7 +10,5 @@
 #include "group.hpp"
 
 namespace tc {
-    constexpr Coset UNBOUNDED = (Coset) (-1);
-
     Cosets solve(const Group &group, const std::vector<Gen> &sub_gens, const Coset &bound = UNBOUNDED);
 }

tc/include/tc/cosets.hpp

@@ -2,17 +2,9 @@
 
 #include <cstdlib>
 
-#include "cosets.hpp"
+#include "util.hpp"
 
 namespace tc {
-    using Coset = uint32_t;
-    using Gen = uint8_t;
-    using Mult = uint16_t;
-    constexpr Mult FREE = Mult(-1);
-    constexpr Coset UNSET = Coset(-1);
-
-    using Rel = std::tuple<Gen, Gen, Mult>;
-
     struct Cosets {
         Gen ngens;
         std::vector<int> data;

tc/include/tc/group.hpp

@@ -1,9 +1,10 @@
 #pragma once
 
+#include <cassert>
 #include <sstream>
 
+#include <tc/util.hpp>
 #include <tc/pair_map.hpp>
-#include <cassert>
 
 namespace tc {
     struct Group;

tc/include/tc/groups.hpp

@@ -1,7 +1,8 @@
 #pragma once
 
-#include "core.hpp"
+#include <vector>
 
+#include <tc/group.hpp>
 
 namespace tc {
     /**
@@ -10,55 +11,13 @@ namespace tc {
      */
     Group schlafli(const std::vector<int> &mults);
 
-    namespace group {
-        /**
-         * Simplex
-         */
-        Group A(int dim);
+    Group coxeter(const std::string &symbol);
 
-        /**
-         * Cube, Orthoplex
-         */
-        Group B(int dim);
+    Group vcoxeter(const std::string &symbol, std::vector<int> &values);
 
-        /**
-         * Demicube, Orthoplex
-         */
-        Group D(int dim);
-
-        /**
-         * E groups
-         */
-        Group E(int dim);
-
-        /**
-         * 24 Cell
-         */
-        Group F4();
-
-        /**
-         * Hexagon
-         */
-        Group G2();
-
-        /**
-         * Icosahedron
-         */
-        Group H(int dim);
-
-        /**
-         * Polygonal
-         */
-        Group I2(int n);
-
-        /**
-         * Toroidal. I2(n) * I2(m)
-         */
-        Group T(int n, int m);
-
-        /**
-         * Toroidal. T(n, n)
-         */
-        Group T(int n);
+    template<typename ...Args>
+    Group coxeter(const std::string &symbol, const Args &... args) {
+        std::vector<int> values = {{args...}};
+        return vcoxeter(symbol, values);
     }
 }

tc/include/tc/util.hpp

@@ -6,6 +6,17 @@
 #include <functional>
 
 namespace tc {
+    using Gen = uint8_t;
+    using Mult = uint16_t;
+
+    constexpr Mult FREE = Mult(-1);
+
+    using Coset = uint32_t;
+    constexpr Coset UNSET = Coset(-1);
+    constexpr Coset UNBOUNDED = (Coset) (-1);
+
+    using Rel = std::tuple<Gen, Gen, Mult>;
+
     struct Action {
         int from_idx = -1;
         int gen = -1;

tc/src/groups.cpp

@@ -1,6 +1,7 @@
-#include <cassert>
+#include <tc/groups.hpp>
 
-#include "tc/groups.hpp"
+#include <fmt/args.h>
+#include <fmt/core.h>
 
 namespace tc {
     Group schlafli(const std::vector<int> &mults) {
@@ -11,74 +12,13 @@ namespace tc {
         return res;
     }
 
-    namespace group {
-        Group A(const int dim) {
-            assert(dim >= 1);
+    Group v_coxeter(const std::string &symbol, std::vector<int> &values) {
+        fmt::dynamic_format_arg_store<fmt::format_context> ds;
 
-            return schlafli(std::vector<int>(dim - 1, 3));
+        for (const auto &value: values) {
+            ds.push_back(value);
         }
 
-        Group B(const int dim) {
-            assert(dim >= 2);
-            
-            std::vector<int> mults(dim - 1, 3);
-            mults[0] = 4;
-
-            return schlafli(mults);
-        }
-
-        Group D(const int dim) {
-            assert(dim >= 4);
-            
-            std::vector<int> mults(dim - 1, 3);
-            mults[dim - 2] = 2;
-
-            Group g = schlafli(mults);
-            g.set(Rel{1, dim - 1, 3});
-
-            return g;
-        }
-
-        Group E(const int dim) {
-            assert(dim >= 6);
-            
-            std::vector<int> mults(dim - 1, 3);
-            mults[dim - 2] = 2;
-
-            Group g = schlafli(mults);
-            g.set(Rel{2, dim - 1, 3});
-
-            return g;
-        }
-
-        Group F4() {
-            return schlafli({3, 4, 3});
-        }
-
-        Group G2() {
-            return schlafli({6});
-        }
-
-        Group H(const int dim) {
-            assert(dim >= 2);
-            assert(dim <= 4);
-            
-            std::vector<int> mults(dim - 1, 3);
-            mults[0] = 5;
-
-            return schlafli(mults);
-        }
-
-        Group I2(const int n) {
-            return schlafli({n});
-        }
-
-        Group T(const int n, const int m) {
-            return schlafli({n, 2, m});
-        }
-
-        Group T(const int n) {
-            return T(n, n);
-        }
+        return coxeter(fmt::vformat(symbol, ds));
     }
 }

tc/src/keep.cpp

@@ -1 +0,0 @@
-#include <tc/pair_map.hpp>

tc/src/lang.cpp

@@ -0,0 +1,289 @@
+#include <vector>
+#include <stack>
+#include <string>
+#include <cassert>
+
+#include <tc/group.hpp>
+#include <tc/groups.hpp>
+
+#include <peglib.h>
+
+#include <fmt/core.h>
+#include <fmt/ranges.h>
+
+struct Op {
+    enum Code {
+        LINK,
+        PUSH,
+        POP,
+        LOOP,
+    };
+
+    Code code: 4;
+    unsigned int value: 12;
+
+    explicit Op(Code code, unsigned int value = 0)
+        : code(code), value(value) {}
+};
+
+template<>
+struct fmt::formatter<Op> {
+    template<typename ParseContext>
+    constexpr auto parse(ParseContext &ctx) {
+        return ctx.begin();
+    }
+
+    template<typename FormatContext>
+    auto format(const Op &op, FormatContext &ctx) {
+        switch (op.code) {
+            case Op::LINK:
+                return fmt::format_to(ctx.out(), "link({})",
+                                      (unsigned int) op.value);
+            case Op::PUSH:
+                return fmt::format_to(ctx.out(), "push()");
+            case Op::POP:
+                return fmt::format_to(ctx.out(), "pop()");
+            case Op::LOOP:
+                return fmt::format_to(ctx.out(), "loop()");
+            default:
+                return fmt::format_to(ctx.out(), "[{}]({})",
+                                      (unsigned int) op.code,
+                                      (unsigned int) op.value);
+        }
+    }
+};
+
+struct Factor {
+    unsigned int mode;
+    std::vector<unsigned int> orders;
+};
+
+struct codegen {
+    std::vector<Op> ops;
+
+    void link(unsigned int order) {
+        ops.emplace_back(Op::LINK, order);
+    }
+
+    void push() {
+        ops.emplace_back(Op::PUSH);
+    }
+
+    void pop() {
+        ops.emplace_back(Op::POP);
+    }
+
+    void loop() {
+        ops.emplace_back(Op::LOOP);
+    }
+
+    template<typename It>
+    void insert(It begin, It end) {
+        std::copy(begin, end, std::back_inserter(ops));
+    }
+
+    void insert(const codegen &o) {
+        insert(o.ops.begin(), o.ops.end());
+    }
+};
+
+static const std::string GRAMMAR = R"(
+    root    <- term+
+    term    <- product / op
+    op      <- block / link
+    block   <- '(' root ')' / '{' root '}' / '[' root ']'
+    link    <- int
+    product <- op '*' factor
+    factor  <- int / '{' int+ '}' / '[' int+ ']'
+    int     <- < [0-9]+ >
+
+    %whitespace <- [ \t\n\r]*
+)";
+
+peg::parser build_parser() {
+    peg::parser parser;
+    parser.set_logger([](size_t line, size_t col, const std::string &msg, const std::string &rule) {
+        fmt::print(stderr, "{}:{} [{}] {}\n", line, col, rule, msg);
+    });
+    auto ok = parser.load_grammar(GRAMMAR);
+    assert(ok);
+
+    parser["int"] = [](const peg::SemanticValues &vs) -> std::any {
+        return vs.token_to_number<unsigned int>();
+    };
+
+    parser["link"] = [](const peg::SemanticValues &vs) -> std::any {
+        codegen cg;
+
+        auto order = std::any_cast<unsigned int>(vs[0]);
+        cg.link(order);
+
+        return cg;
+    };
+
+    parser["root"] = [](const peg::SemanticValues &vs) -> std::any {
+        codegen cg;
+
+        for (const auto &sub: vs) {
+            cg.insert(std::any_cast<codegen>(sub));
+        }
+
+        return cg;
+    };
+
+    parser["block"] = [](const peg::SemanticValues &vs) -> std::any {
+        if (vs.choice() == 0) return vs[0];
+
+        codegen cg;
+
+        cg.push();
+        cg.insert(std::any_cast<codegen>(vs[0]));
+        if (vs.choice() == 1) cg.loop();
+        cg.pop();
+
+        return cg;
+    };
+
+    parser["factor"] = [](const peg::SemanticValues &vs) -> std::any {
+        return Factor{
+            (unsigned int) vs.choice(),
+            vs.transform<unsigned int>(),
+        };
+    };
+
+    parser["product"] = [](const peg::SemanticValues &vs) -> std::any {
+        auto sub = std::any_cast<codegen>(vs[0]);
+        auto fac = std::any_cast<Factor>(vs[1]);
+
+        codegen cg;
+
+        for (const auto &order: fac.orders) {
+            if (fac.mode == 0) {
+                for (unsigned int i = 0; i < order; ++i) {
+                    cg.insert(sub);
+                }
+            } else {
+                cg.push();
+                for (unsigned int i = 0; i < order; ++i) {
+                    cg.insert(sub);
+                }
+                if (fac.mode == 1) cg.loop();
+                cg.pop();
+            }
+        }
+
+        return cg;
+    };
+
+    return parser;
+}
+
+#ifndef NDEBUG
+peg::parser build_ast_parser() {
+    peg::parser parser;
+    parser.set_logger([](size_t line, size_t col, const std::string &msg, const std::string &rule) {
+        fmt::print(stderr, "{}:{} [{}] {}\n", line, col, rule, msg);
+    });
+    auto ok = parser.load_grammar(GRAMMAR);
+    assert(ok);
+
+    parser.enable_ast();
+
+    return parser;
+}
+#endif
+
+std::vector<Op> compile(const std::string &source) {
+#ifndef NDEBUG
+    static peg::parser ast_parser = build_ast_parser();
+    std::shared_ptr<peg::Ast> ast;
+    bool ast_ok = ast_parser.parse(source, ast);
+    assert(ast_ok);
+    std::cout << peg::ast_to_s(ast) << std::endl;
+#endif
+
+    static peg::parser parser = build_parser();
+    codegen cg;
+    bool ok = parser.parse(source, cg);
+    assert(ok);
+    return cg.ops;
+}
+
+struct Graph {
+    size_t rank{};
+    std::vector<std::tuple<size_t, size_t, unsigned int>> edges{};
+};
+
+Graph eval(const std::vector<Op> &ops) {
+    std::vector<std::stack<size_t>> stacks(1);
+
+    Graph g;
+    stacks.back().emplace(g.rank++);
+
+    for (const auto &op: ops) {
+        switch (op.code) {
+            case Op::LINK: {
+                auto order = op.value;
+
+                auto top = stacks.back().top();
+                auto curr = g.rank++;
+
+                stacks.back().emplace(curr);
+                g.edges.emplace_back(top, curr, order);
+
+                break;
+            }
+            case Op::PUSH: {
+                stacks.emplace_back();
+
+                auto ptop = stacks[stacks.size() - 2].top();
+                stacks.back().emplace(ptop);
+
+                break;
+            }
+            case Op::POP: {
+                stacks.pop_back();
+
+                break;
+            }
+            case Op::LOOP: {
+                g.rank--;
+
+                auto ptop = stacks[stacks.size() - 2].top();
+                auto &[top, _, order] = g.edges.back();
+
+                stacks.back().pop();
+                g.edges.pop_back();
+
+                g.edges.emplace_back(top, ptop, order);
+
+                break;
+            }
+            default:
+                throw std::runtime_error("Invalid opcode");
+        }
+    }
+
+    return g;
+}
+
+namespace tc {
+    Group coxeter(const std::string &symbol) {
+        auto ops = compile(symbol);
+
+//        fmt::print("#ops: {}\n", ops.size());
+//        for (const auto &op: ops) {
+//            fmt::print(" {}\n", op);
+//        }
+        
+        auto diagram = eval(ops);
+
+        Group res((int) diagram.rank);
+
+        for (const auto &[i, j, order]: diagram.edges) {
+            res.set({i, j, order});
+        }
+
+        return res;
+    }
+}

tc/src/langtest.cpp

@@ -0,0 +1,39 @@
+#include <iostream>
+
+#include <tc/group.hpp>
+#include <tc/groups.hpp>
+
+int main() {
+    std::vector<std::string> symbols = {
+        "5 3 3",
+        "5 (3 3)",
+        "[5 3 3]",
+        "[4 3 [3 5] 3]",
+        "{3 4 5 6 7 8 9}",
+        "3 {3 3 [4] 3} 5",
+        "5 * 3",
+        "5 * [3]",
+        "5 * {2 3}",
+        "5 * [3 2]",
+        "(5 2) * [3 2]",
+        "4 [3 * [2 3]] 5",
+        "{3 * 3} [4] [5]",
+    };
+
+    for (const auto &symbol: symbols) {
+        auto group = tc::coxeter(symbol);
+        
+        std::cout << "'" << symbol << "'" << std::endl;
+
+        for (int i = 0; i < group.ngens; ++i) {
+            for (int j = 0; j < group.ngens; ++j) {
+                std::cout << group.get(i, j) << " ";
+            }
+            std::cout << std::endl;
+        }
+        
+        std::cout << "===========================" << std::endl;
+    }
+    
+    return EXIT_SUCCESS;
+}

tc/src/pegtest.cpp

@@ -0,0 +1,280 @@
+#include <vector>
+#include <stack>
+#include <string>
+
+#include <fmt/core.h>
+#include <fmt/ranges.h>
+
+#include <peglib.h>
+
+struct Op {
+    enum Code {
+        LINK,
+        PUSH,
+        POP,
+        LOOP,
+    };
+
+    Code code: 4;
+    unsigned int value: 12;
+
+    explicit Op(Code code, unsigned int value = 0)
+        : code(code), value(value) {}
+};
+
+template<>
+struct fmt::formatter<Op> {
+    template<typename ParseContext>
+    constexpr auto parse(ParseContext &ctx) {
+        return ctx.begin();
+    }
+
+    template<typename FormatContext>
+    auto format(const Op &op, FormatContext &ctx) {
+        switch (op.code) {
+            case Op::LINK:
+                return fmt::format_to(ctx.out(), "link({})",
+                                      (unsigned int) op.value);
+            case Op::PUSH:
+                return fmt::format_to(ctx.out(), "push()");
+            case Op::POP:
+                return fmt::format_to(ctx.out(), "pop()");
+            case Op::LOOP:
+                return fmt::format_to(ctx.out(), "loop()");
+            default:
+                return fmt::format_to(ctx.out(), "[{}]({})",
+                                      (unsigned int) op.code,
+                                      (unsigned int) op.value);
+        }
+    }
+};
+
+struct Factor {
+    unsigned int mode;
+    std::vector<unsigned int> orders;
+};
+
+struct codegen {
+    std::vector<Op> ops;
+
+    void link(unsigned int order) {
+        ops.emplace_back(Op::LINK, order);
+    }
+
+    void push() {
+        ops.emplace_back(Op::PUSH);
+    }
+
+    void pop() {
+        ops.emplace_back(Op::POP);
+    }
+
+    void loop() {
+        ops.emplace_back(Op::LOOP);
+    }
+
+    template<typename It>
+    void insert(It begin, It end) {
+        std::copy(begin, end, std::back_inserter(ops));
+    }
+
+    void insert(const codegen &o) {
+        insert(o.ops.begin(), o.ops.end());
+    }
+};
+
+peg::parser build_parser() {
+    const auto grammar = R"(
+        root    <- term+
+        term    <- product / op
+        op      <- block / link
+        block   <- '(' root ')' / '{' root '}' / '[' root ']'
+        link    <- int
+        product <- op '*' factor
+        factor  <- int / '{' int+ '}' / '[' int+ ']'
+        int     <- < [0-9]+ >
+
+        %whitespace <- [ \t\n\r]*
+    )";
+
+    peg::parser parser;
+    parser.set_logger([](size_t line, size_t col, const std::string &msg, const std::string &rule) {
+        fmt::print(stderr, "{}:{} [{}] {}\n", line, col, rule, msg);
+    });
+    auto ok = parser.load_grammar(grammar);
+    assert(ok);
+
+    parser["int"] = [](const peg::SemanticValues &vs) -> std::any {
+        return vs.token_to_number<unsigned int>();
+    };
+
+    parser["link"] = [](const peg::SemanticValues &vs) -> std::any {
+        codegen cg;
+
+        auto order = std::any_cast<unsigned int>(vs[0]);
+        cg.link(order);
+
+        return cg;
+    };
+
+    parser["root"] = [](const peg::SemanticValues &vs) -> std::any {
+        codegen cg;
+
+        for (const auto &sub: vs) {
+            cg.insert(std::any_cast<codegen>(sub));
+        }
+
+        return cg;
+    };
+
+    parser["block"] = [](const peg::SemanticValues &vs) -> std::any {
+        if (vs.choice() == 0) return vs[0];
+
+        codegen cg;
+
+        cg.push();
+        cg.insert(std::any_cast<codegen>(vs[0]));
+        if (vs.choice() == 1) cg.loop();
+        cg.pop();
+
+        return cg;
+    };
+
+    parser["factor"] = [](const peg::SemanticValues &vs) -> std::any {
+        return Factor{
+            (unsigned int) vs.choice(),
+            vs.transform<unsigned int>(),
+        };
+    };
+
+    parser["product"] = [](const peg::SemanticValues &vs) -> std::any {
+        auto sub = std::any_cast<codegen>(vs[0]);
+        auto fac = std::any_cast<Factor>(vs[1]);
+
+        codegen cg;
+
+        for (const auto &order: fac.orders) {
+            if (fac.mode == 0) {
+                for (unsigned int i = 0; i < order; ++i) {
+                    cg.insert(sub);
+                }
+            } else {
+                cg.push();
+                for (unsigned int i = 0; i < order; ++i) {
+                    cg.insert(sub);
+                }
+                if (fac.mode == 1) cg.loop();
+                cg.pop();
+            }
+        }
+
+        return cg;
+    };
+
+    return parser;
+}
+
+std::vector<Op> compile(const std::string &source) {
+    static peg::parser parser = build_parser();
+
+    std::any val;
+    codegen cg;
+
+    bool success = parser.parse(source, cg);
+    assert(success);
+
+    return cg.ops;
+}
+
+struct Graph {
+    size_t rank{};
+    std::vector<std::tuple<size_t, size_t, unsigned int>> edges{};
+};
+
+Graph eval(const std::vector<Op> &ops) {
+    std::vector<std::stack<size_t>> stacks(1);
+
+    Graph g;
+    stacks.back().emplace(g.rank++);
+
+    for (const auto &op: ops) {
+        switch (op.code) {
+            case Op::LINK: {
+                auto order = op.value;
+
+                auto top = stacks.back().top();
+                auto curr = g.rank++;
+
+                stacks.back().emplace(curr);
+                g.edges.emplace_back(top, curr, order);
+
+                break;
+            }
+            case Op::PUSH: {
+                stacks.emplace_back();
+
+                auto ptop = stacks[stacks.size() - 2].top();
+                stacks.back().emplace(ptop);
+
+                break;
+            }
+            case Op::POP: {
+                stacks.pop_back();
+
+                break;
+            }
+            case Op::LOOP: {
+                g.rank--;
+
+                auto ptop = stacks[stacks.size() - 2].top();
+                auto &[top, _, order] = g.edges.back();
+
+                stacks.back().pop();
+                g.edges.pop_back();
+
+                g.edges.emplace_back(top, ptop, order);
+
+                break;
+            }
+            default:
+                throw std::runtime_error("Invalid opcode");
+        }
+    }
+
+    return g;
+}
+
+int main() {
+    std::vector<std::string> sources = {
+        "5 3 3",
+        "5 (3 3)",
+        "[5 3 3]",
+        "[4 3 [3 5] 3]",
+        "{3 4 3 5}",
+        "3 {3 3 [4] 3} 5",
+        "5 * 3",
+        "5 * [3]",
+        "5 * {2 3}",
+        "5 * [3 2]",
+        "(5 2) * [3 2]",
+        "4 [3 * [2 3]] 5",
+        "{3 * 3} [4] [5]",
+    };
+
+    for (const auto &source: sources) {
+        fmt::print("source: '{}'\n", source);
+
+        auto ops = compile(source);
+        for (const auto &op: ops) {
+            fmt::print("-  {}\n", op);
+        }
+        auto g = eval(ops);
+        fmt::print("rank: {}\n", g.rank);
+        for (const auto &edge: g.edges) {
+            fmt::print("- {}\n", edge);
+        }
+        fmt::print("=======================================\n");
+    }
+
+    return 0;
+}