feat(api): add APIs for parsing files, commands and expressions

src/api/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_library(api OBJECT string.cpp exception.cpp name.cpp options.cpp univ.cpp
-  expr.cpp decl.cpp env.cpp ios.cpp module.cpp type_checker.cpp inductive.cpp)
+  expr.cpp decl.cpp env.cpp ios.cpp module.cpp type_checker.cpp inductive.cpp
+  parser.cpp)
 
 FILE(GLOB LEAN_API_INCLUDE_FILES lean*.h)
 install(FILES ${LEAN_API_INCLUDE_FILES} DESTINATION include)

src/api/lean.h

@@ -21,5 +21,6 @@ Author: Leonardo de Moura
 #include "lean_module.h"        // NOLINT
 #include "lean_type_checker.h"  // NOLINT
 #include "lean_inductive.h"     // NOLINT
+#include "lean_parser.h"        // NOLINT
 
 #endif

src/api/lean_parser.h

@@ -0,0 +1,44 @@
+/*
+Copyright (c) 2015 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+#ifndef _LEAN_PARSER_H
+#define _LEAN_PARSER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+   \defgroup capi C API
+*/
+/*@{*/
+
+/**
+   @name Parser API
+*/
+/*@{*/
+
+/** \brief Parse the file \c fname using \c env and \c ios.
+    Store the updated environment and ios at \c new_env and \c new_ios.
+    \remark We return a new ios object because Lean has commands for updating configuration options. */
+lean_bool lean_parse_file(lean_env env, lean_ios ios, char const * fname, lean_env * new_env, lean_ios * new_ios, lean_exception * ex);
+
+/** \brief Parse the commands in the string \c str using \c env and \c ios.
+    Store the updated environment and ios at \c new_env and \c new_ios.
+    \remark We return a new ios object because Lean has commands for updating configuration options. */
+lean_bool lean_parse_commands(lean_env env, lean_ios ios, char const * str, lean_env * new_env, lean_ios * new_ios, lean_exception * ex);
+
+/** \brief Parse (and elaborate) the expression in the string \c str using \c env and \c ios.
+    Store the elaborated expression in \c new_expr, and automatically generated universe parameters in \c new_ps. */
+lean_bool lean_parse_expr(lean_env env, lean_ios ios, char const * str, lean_expr * new_expr, lean_list_name * new_ps, lean_exception * ex);
+
+/*@}*/
+/*@}*/
+
+#ifdef __cplusplus
+};
+#endif
+#endif

src/api/parser.cpp

@@ -0,0 +1,65 @@
+/*
+Copyright (c) 2015 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+
+Author: Leonardo de Moura
+*/
+#include "frontends/lean/parser.h"
+#include "api/string.h"
+#include "api/exception.h"
+#include "api/decl.h"
+#include "api/ios.h"
+#include "api/lean_parser.h"
+using namespace lean; // NOLINT
+
+lean_bool lean_parse_file(lean_env env, lean_ios ios, char const * fname, lean_env * new_env, lean_ios * new_ios, lean_exception * ex) {
+    LEAN_TRY;
+    check_nonnull(env);
+    check_nonnull(ios);
+    check_nonnull(fname);
+    environment _env     = to_env_ref(env);
+    io_state    _ios     = to_io_state_ref(ios);
+    bool use_exceptions  = true;
+    unsigned num_threads = 1;
+    parse_commands(_env, _ios, fname, use_exceptions, num_threads);
+    *new_env = of_env(new environment(_env));
+    *new_ios = of_io_state(new io_state(_ios));
+    LEAN_CATCH;
+}
+
+lean_bool lean_parse_commands(lean_env env, lean_ios ios, char const * str, lean_env * new_env, lean_ios * new_ios, lean_exception * ex) {
+    LEAN_TRY;
+    check_nonnull(env);
+    check_nonnull(ios);
+    check_nonnull(str);
+    std::istringstream in(str);
+    char const * strname = "[string]";
+    environment _env     = to_env_ref(env);
+    io_state    _ios     = to_io_state_ref(ios);
+    bool use_exceptions  = true;
+    unsigned num_threads = 1;
+    parse_commands(_env, _ios, in, strname, use_exceptions, num_threads);
+    *new_env = of_env(new environment(_env));
+    *new_ios = of_io_state(new io_state(_ios));
+    LEAN_CATCH;
+}
+
+lean_bool lean_parse_expr(lean_env env, lean_ios ios, char const * str, lean_expr * new_expr, lean_list_name * new_ps, lean_exception * ex) {
+    LEAN_TRY;
+    check_nonnull(env);
+    check_nonnull(ios);
+    check_nonnull(str);
+    std::istringstream in(str);
+    char const * strname = "[string]";
+    environment _env     = to_env_ref(env);
+    io_state    _ios     = to_io_state_ref(ios);
+    bool use_exceptions  = true;
+    unsigned num_threads = 1;
+    parser p(_env, _ios, in, strname, use_exceptions, num_threads);
+    expr e = p.parse_expr();
+    expr _e; level_param_names _ps;
+    std::tie(_e, _ps) = p.elaborate(e, list<expr>());
+    *new_expr = of_expr(new expr(_e));
+    *new_ps   = of_list_name(new list<name>(_ps));
+    LEAN_CATCH;
+}

src/tests/shared/env.c

@@ -464,11 +464,59 @@ void test_inductive() {
     lean_env_del(new_env);
 }
 
+void test_parser() {
+    lean_exception ex = 0;
+    lean_env env      = mk_env();
+    lean_ios ios;
+    lean_env new_env;
+    lean_ios new_ios;
+    lean_options o;
+    check(lean_options_mk_empty(&o, &ex));
+    check(lean_ios_mk_std(o, &ios, &ex));
+    check(lean_parse_commands(env, ios, "import standard open nat definition double (a : nat) := a + a check double 4 eval double 4",
+                              &new_env, &new_ios, &ex));
+    {
+        lean_name double_name = mk_name("double");
+        lean_decl double_decl;
+        lean_expr double_decl_value;
+        char const * s;
+        check(lean_env_get_decl(new_env, double_name, &double_decl, &ex));
+        check(lean_decl_get_value(double_decl, &double_decl_value, &ex));
+        check(lean_expr_to_pp_string(new_env, new_ios, double_decl_value, &s, &ex));
+        printf("definition of double\n%s\n", s);
+        lean_name_del(double_name);
+        lean_decl_del(double_decl);
+        lean_expr_del(double_decl_value);
+        lean_string_del(s);
+    }
+
+    {
+        lean_expr e;
+        lean_list_name ps;
+        // remark: we can use notation from the namespace nat because we have executed 'open nat'
+        // when we created new_env
+        check(lean_parse_expr(new_env, new_ios, "double (2 + 3)", &e, &ps, &ex));
+        char const * s;
+        check(lean_expr_to_pp_string(new_env, new_ios, e, &s, &ex));
+        printf("parsed expression: %s\n", s);
+        lean_string_del(s);
+        lean_expr_del(e);
+        lean_list_name_del(ps);
+    }
+
+    lean_options_del(o);
+    lean_env_del(env);
+    lean_env_del(new_env);
+    lean_ios_del(ios);
+    lean_ios_del(new_ios);
+}
+
 int main() {
     test_add_univ();
     test_id();
     test_path();
     test_import();
     test_inductive();
+    test_parser();
     return 0;
 }