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cpp-peglib
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Updated documentation and examples.

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yhirose 9 years ago
parent e30b4a281f
commit 6c59c02ea9
4 changed files with 22 additions and 54 deletions
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  1. 18
      README.md
  2. 24
      example/calc.cc
  3. 7
      example/calc2.cc
  4. 27
      example/calc3.cc

18
README.md
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@ -21,16 +21,14 @@ How to use
This is a simple calculator sample. It shows how to define grammar, associate samantic actions to the grammar and handle semantic values.
```c++
#include <assert.h>
// (1) Include the header file
#include <peglib.h>
#include <assert.h>
using namespace peglib;
using namespace std;
int main(void) {
// (2) Make a parser
auto syntax = R"(
# Grammar for Calculator...
@ -42,22 +40,20 @@ int main(void) {
peg parser(syntax);
parser.packrat_parsing(true); // Enable packrat parsing
// (3) Setup an action
parser["Additive"] = {
nullptr, // Default action
nullptr, // Default action
[](const SemanticValues& sv) {
return sv[0].get<int>() + sv[1].get<int>(); // 1st choice
return sv[0].get<int>() + sv[1].get<int>(); // "Multitive '+' Additive"
},
[](const SemanticValues& sv) { return sv[0]; } // 2nd choice
[](const SemanticValues& sv) { return sv[0]; } // "Multitive"
};
parser["Multitive"] = [](const SemanticValues& sv) {
switch (sv.choice) {
case 0: // 1st choice
case 0: // "Multitive '+' Additive"
return sv[0].get<int>() * sv[1].get<int>();
default: // 2nd choice
default: // "Multitive"
return sv[0].get<int>();
}
};
@ -67,6 +63,8 @@ int main(void) {
};
// (4) Parse
parser.packrat_parsing(true); // Enable packrat parsing.
int val;
parser.parse("(1+2)*3", val);

24
example/calc.cc
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@ -12,17 +12,6 @@
using namespace peglib;
using namespace std;
//
// PEG syntax:
//
// EXPRESSION <- _ TERM (TERM_OPERATOR TERM)*
// TERM <- FACTOR (FACTOR_OPERATOR FACTOR)*
// FACTOR <- NUMBER / '(' _ EXPRESSION ')' _
// TERM_OPERATOR <- < [-+] > _
// FACTOR_OPERATOR <- < [/*] > _
// NUMBER <- < [0-9]+ > _
// ~_ <- [ \t\r\n]*
//
int main(int argc, const char** argv)
{
if (argc < 2 || string("--help") == argv[1]) {
@ -30,8 +19,6 @@ int main(int argc, const char** argv)
return 1;
}
const char* s = argv[1];
auto reduce = [](const SemanticValues& sv) -> long {
auto result = sv[0].get<long>();
for (auto i = 1u; i < sv.size(); i += 2) {
@ -47,7 +34,7 @@ int main(int argc, const char** argv)
return result;
};
const char* syntax =
peg parser(
" EXPRESSION <- _ TERM (TERM_OPERATOR TERM)* "
" TERM <- FACTOR (FACTOR_OPERATOR FACTOR)* "
" FACTOR <- NUMBER / '(' _ EXPRESSION ')' _ "
@ -55,9 +42,7 @@ int main(int argc, const char** argv)
" FACTOR_OPERATOR <- < [/*] > _ "
" NUMBER <- < [0-9]+ > _ "
" ~_ <- [ \t\r\n]* "
;
peg parser(syntax);
);
parser["EXPRESSION"] = reduce;
parser["TERM"] = reduce;
@ -65,9 +50,10 @@ int main(int argc, const char** argv)
parser["FACTOR_OPERATOR"] = [](const char* s, size_t n) { return (char)*s; };
parser["NUMBER"] = [](const char* s, size_t n) { return atol(s); };
auto expr = argv[1];
long val = 0;
if (parser.parse(s, val)) {
cout << s << " = " << val << endl;
if (parser.parse(expr, val)) {
cout << expr << " = " << val << endl;
return 0;
}

7
example/calc2.cc
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@ -29,8 +29,6 @@ int main(int argc, const char** argv)
return 1;
}
const char* s = argv[1];
auto reduce = [](const SemanticValues& sv) -> long {
auto result = sv[0].get<long>();
for (auto i = 1u; i < sv.size(); i += 2) {
@ -55,9 +53,10 @@ int main(int argc, const char** argv)
FACTOR_OPERATOR <= cls("*/"), [](const char* s, size_t n) { return (char)*s; };
NUMBER <= oom(cls("0-9")), [](const char* s, size_t n) { return atol(s); };
auto expr = argv[1];
long val = 0;
if (EXPRESSION.parse_and_get_value(s, val).ret) {
cout << s << " = " << val << endl;
if (EXPRESSION.parse_and_get_value(expr, val).ret) {
cout << expr << " = " << val << endl;
return 0;
}

27
example/calc3.cc
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@ -12,24 +12,12 @@
using namespace peglib;
using namespace std;
//
// PEG syntax:
//
// EXPRESSION <- _ TERM (TERM_OPERATOR TERM)*
// TERM <- FACTOR (FACTOR_OPERATOR FACTOR)*
// FACTOR <- NUMBER / '(' _ EXPRESSION ')' _
// TERM_OPERATOR <- < [-+] > _
// FACTOR_OPERATOR <- < [/*] > _
// NUMBER <- < [0-9]+ > _
// ~_ <- [ \t\r\n]*
//
template <typename T, typename U, typename F>
static U reduce(T i, T end, U val, F f) {
if (i == end) {
return val;
}
std::tie(val, i) = f(val, i);
tie(val, i) = f(val, i);
return reduce(i, end, val, f);
};
@ -96,9 +84,7 @@ int main(int argc, const char** argv)
return 1;
}
const char* s = argv[1];
const char* syntax =
peg parser(
" EXPRESSION <- _ TERM (TERM_OPERATOR TERM)* "
" TERM <- FACTOR (FACTOR_OPERATOR FACTOR)* "
" FACTOR <- NUMBER / '(' _ EXPRESSION ')' _ "
@ -106,9 +92,7 @@ int main(int argc, const char** argv)
" FACTOR_OPERATOR <- < [/*] > _ "
" NUMBER <- < [0-9]+ > _ "
" ~_ <- [ \t\r\n]* "
;
peg parser(syntax);
);
parser["EXPRESSION"] = ast_ope::create;
parser["TERM"] = ast_ope::create;
@ -116,9 +100,10 @@ int main(int argc, const char** argv)
parser["FACTOR_OPERATOR"] = [](const char* s, size_t n) { return *s; };
parser["NUMBER"] = ast_num::create;
auto expr = argv[1];
shared_ptr<ast_node> ast;
if (parser.parse(s, ast)) {
cout << s << " = " << ast->eval() << endl;
if (parser.parse(expr, ast)) {
cout << expr << " = " << ast->eval() << endl;
return 0;
}

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