Test multiple starting rules

doc/user_guide.md

@@ -738,6 +738,22 @@ Example:
 start MyStartRule;
 ```
 
+Multiple start rules can be specified, either with multiple `start` statements
+or one `start` statement listing multiple start rules.
+Example:
+
+```
+start Module ModuleItem Statement Expression;
+```
+
+When multiple start rules are specified, multiple `p_parse_*()` functions,
+`p_result_*()`, and `p_free_ast_*()` functions (in AST mode) are generated.
+A default `p_parse()`, `p_result()`, `p_free_ast()` are generated corresponding
+to the first start rule.
+Additionally, each start rule causes the generation of another version of each
+of these functions, for example `p_parse_Statement()`, `p_result_Statement()`,
+and `p_free_ast_Statement()`.
+
 ##> Specifying the parser module name - the `module` statement
 
 The `module` statement can be used to specify the module name for a generated
@@ -1018,6 +1034,16 @@ p_context_init(&context, input, input_length);
 size_t result = p_parse(&context);
 ```
 
+When multiple start rules are specified, a separate parse function is generated
+for each which starts parsing at the given rule.
+For example, if `Statement` is specified as a start rule:
+
+```
+size_t result = p_parse_Statement(&context);
+```
+
+In this case, the parser will start parsing with the `Statement` rule.
+
 ### `p_position_valid`
 
 The `p_position_valid()` function is only generated for C targets.
@@ -1056,6 +1082,23 @@ if (p_parse(&context) == P_SUCCESS)
 If AST generation mode is active, then the `p_result()` function returns a
 `Start *` pointing to the `Start` AST structure.
 
+When multiple start rules are specified, a separate result function is generated
+for each which returns the parse result for the corresponding rule.
+For example, if `Statement` is specified as a start rule:
+
+```
+p_context_t context;
+p_context_init(&context, input, input_length);
+size_t result = p_parse(&context);
+if (p_parse_Statement(&context) == P_SUCCESS)
+{
+    result = p_result_Statement(&context);
+}
+```
+
+In this case, the parser will start parsing with the `Statement` rule and the
+parse result from the `Statement` rule will be returned.
+
 ### `p_position`
 
 The `p_position()` function can be used to retrieve the parser position where
@@ -1142,6 +1185,17 @@ If specified, the `free_token_node` function will be called during the
 `p_free_ast()` process to allow user code to free any memory associated with
 a token node's `pvalue`.
 
+When multiple start rules are specified, a separate `p_free_ast` function is
+generated for each which frees the AST resulting from parsing the given rule.
+For example, if `Statement` is specified as a start rule:
+
+```
+p_free_ast_Statement(statement_ast);
+```
+
+In this case, Propane will free a `Statement` AST structure returned by the
+`p_parse_Statement(&context)` function.
+
 ##> Data
 
 ### `p_token_names`

lib/propane/grammar.rb

@@ -242,8 +242,11 @@ class Propane
     end
 
     def parse_start_statement!
-      if md = consume!(/start\s+(\w+)\s*;/)
-        @start_rules << md[1] unless @start_rules.include?(md[1])
+      if md = consume!(/start\s+([\w\s]*);/)
+        start_rules = md[1].split(/\s+/).map(&:strip)
+        start_rules.each do |start_rule|
+          @start_rules << start_rule unless @start_rules.include?(start_rule)
+        end
       end
     end
 

spec/propane_spec.rb

@@ -1440,6 +1440,47 @@ EOF
         expect(results.status).to eq 0
       end
 
+      it "allows multiple starting rules" do
+    write_grammar <<EOF
+ptype int;
+token a << $$ = 1; >>
+token b << $$ = 2; >>
+token c << $$ = 3; >>
+Start -> a b R;
+Start -> Bs:bs << $$ = $1; >>
+R -> c:c << $$ = $1; >>
+Bs -> << $$ = 0; >>
+Bs -> b:b Bs:bs << $$ = $1 + $2; >>
+start Start R Bs;
+EOF
+        run_propane(language: language)
+        compile("spec/test_starting_rules.#{language}", language: language)
+        results = run_test(language: language)
+        expect(results.stderr).to eq ""
+        expect(results.status).to eq 0
+      end
+
+      it "allows multiple starting rules in AST mode" do
+    write_grammar <<EOF
+ast;
+ptype int;
+token a << $$ = 1; >>
+token b << $$ = 2; >>
+token c << $$ = 3; >>
+Start -> a b R;
+Start -> Bs:bs;
+R -> c:c;
+Bs -> ;
+Bs -> b:b Bs:bs;
+start Start R Bs;
+EOF
+        run_propane(language: language)
+        compile("spec/test_starting_rules_ast.#{language}", language: language)
+        results = run_test(language: language)
+        expect(results.stderr).to eq ""
+        expect(results.status).to eq 0
+      end
+
       if %w[c cpp].include?(language)
         it "allows a user function to free token node memory in AST mode" do
     write_grammar <<EOF

spec/test_starting_rules.c

@@ -0,0 +1,27 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+#include "testutils.h"
+
+int main()
+{
+    char const * input = "bbbb";
+    p_context_t context;
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    int result = p_result(&context);
+    assert_eq(8, result);
+
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse_Bs(&context) == P_SUCCESS);
+    result = p_result_Bs(&context);
+    assert_eq(8, result);
+
+    input = "c";
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse_R(&context) == P_SUCCESS);
+    result = p_result_R(&context);
+    assert_eq(3, result);
+
+    return 0;
+}

spec/test_starting_rules.d

@@ -0,0 +1,29 @@
+import testparser;
+import std.stdio;
+import testutils;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "bbbb";
+    p_context_t context;
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    int result = p_result(&context);
+    assert(result == 8);
+
+    p_context_init(&context, input);
+    assert(p_parse_Bs(&context) == P_SUCCESS);
+    result = p_result_Bs(&context);
+    assert(result == 8);
+
+    input = "c";
+    p_context_init(&context, input);
+    assert(p_parse_R(&context) == P_SUCCESS);
+    result = p_result_R(&context);
+    assert(result == 3);
+}

spec/test_starting_rules_ast.c

@@ -0,0 +1,37 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+#include "testutils.h"
+
+int main()
+{
+    char const * input = "bbbb";
+    p_context_t context;
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+    assert_not_null(start->bs);
+    assert_not_null(start->bs->b);
+    assert_not_null(start->bs->bs->b);
+    assert_not_null(start->bs->bs->bs->b);
+    assert_not_null(start->bs->bs->bs->bs->b);
+    p_free_ast(start);
+
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse_Bs(&context) == P_SUCCESS);
+    Bs * bs = p_result_Bs(&context);
+    assert_not_null(bs->b);
+    assert_not_null(bs->bs->b);
+    assert_not_null(bs->bs->bs->b);
+    assert_not_null(bs->bs->bs->bs->b);
+    p_free_ast_Bs(bs);
+
+    input = "c";
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse_R(&context) == P_SUCCESS);
+    R * r = p_result_R(&context);
+    assert_not_null(r->c);
+    p_free_ast_R(r);
+
+    return 0;
+}

spec/test_starting_rules_ast.d

@@ -0,0 +1,36 @@
+import testparser;
+import std.stdio;
+import testutils;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "bbbb";
+    p_context_t context;
+    p_context_init(&context, input);
+    assert(p_parse(&context) == P_SUCCESS);
+    Start * start = p_result(&context);
+    assert(start.bs);
+    assert(start.bs.b);
+    assert(start.bs.bs.b);
+    assert(start.bs.bs.bs.b);
+    assert(start.bs.bs.bs.bs.b);
+
+    p_context_init(&context, input);
+    assert(p_parse_Bs(&context) == P_SUCCESS);
+    Bs * bs = p_result_Bs(&context);
+    assert(bs.b);
+    assert(bs.bs.b);
+    assert(bs.bs.bs.b);
+    assert(bs.bs.bs.bs.b);
+
+    input = "c";
+    p_context_init(&context, input);
+    assert(p_parse_R(&context) == P_SUCCESS);
+    R * r = p_result_R(&context);
+    assert(r.c);
+}

spec/testutils.c

@@ -14,6 +14,24 @@ void assert_eq_size_t_i(size_t expected, size_t actual, char const * file, size_
     }
 }
 
+void assert_ne_size_t_i(size_t expected, size_t actual, char const * file, size_t line)
+{
+    if (expected == actual)
+    {
+        fprintf(stderr, "%s:%lu: expected not %lu, got %lu\n", file, line, expected, actual);
+        assert(false);
+    }
+}
+
+void assert_not_null_i(void * ptr, char const * file, size_t line)
+{
+    if (ptr == NULL)
+    {
+        fprintf(stderr, "%s:%lu: expected not NULL\n", file, line);
+        assert(false);
+    }
+}
+
 void str_init(str_t * str, char const * cs)
 {
     size_t length = strlen(cs);

spec/testutils.h

@@ -5,6 +5,16 @@ void assert_eq_size_t_i(size_t expected, size_t actual, char const * file, size_
 #define assert_eq(expected, actual) \
     assert_eq_size_t_i(expected, actual, __FILE__, __LINE__)
 
+void assert_ne_size_t_i(size_t expected, size_t actual, char const * file, size_t line);
+
+#define assert_ne(expected, actual) \
+    assert_ne_size_t_i(expected, actual, __FILE__, __LINE__)
+
+void assert_not_null_i(void * ptr, char const * file, size_t line);
+
+#define assert_not_null(ptr) \
+    assert_not_null_i(ptr, __FILE__, __LINE__)
+
 typedef struct
 {
     char * cs;