Initial commit.

.gitignore

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+*.o
+*.so
+*.gcda
+*.gcno
+*.gcov

.travis.yml

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+language: c
+dist: xenial
+os: linux
+
+env:
+  global:
+    - ROCKSPEC=rockspecs/lua-fmt-scm-1.rockspec
+  jobs:
+    - LUA="lua 5.1"
+    - LUA="lua 5.2"
+    - LUA="lua 5.3"
+    - LUA="lua 5.4"
+    - LUA="luajit 2.0"
+    - LUA="luajit 2.1"
+
+branches:
+  only:
+    - master
+
+before_install:
+  - pip install --user urllib3[secure] cpp-coveralls
+  - curl -O https://raw.githubusercontent.com/luarocks/hererocks/master/hererocks.py
+  - python hererocks.py env --$LUA -rlatest
+  - source env/bin/activate
+
+install:
+  - luarocks make $ROCKSPEC CFLAGS="-O3 -fPIC -Wall -Wextra --coverage" LIBFLAG="-shared --coverage"
+
+script: 
+  - lua test.lua
+
+after_success:
+    - coveralls
+
+notifications:
+  email:
+    on_success: change
+    on_failure: always
+
+# vim: ft=yaml nu et sw=2 fdc=2 fdm=syntax

README.md

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+# lua-fmt - A fmtlib implement for Lua
+
+[![Build Status](https://travis-ci.org/starwing/lua-fmt.svg?branch=master)](https://travis-ci.org/starwing/lua-fmt)[![Coverage Status](https://coveralls.io/repos/github/starwing/lua-fmt/badge.svg?branch=master)](https://coveralls.io/github/starwing/lua-fmt?branch=master)
+
+
+Lua-fmt is a fmt like simple C module for Lua to format string.
+
+The format syntax is same with
+[fmtlib](https://fmt.dev/latest/syntax.html), which is same with
+Python's `format` routine.
+
+## Install
+
+The simplest way to install it is using Luarocks:
+
+```shell
+luarocks install --server=https://luarocks.org/dev lua-fmt
+```
+
+Or, just compile the single C file:
+
+```shell
+# Linux
+gcc -o lfmt.so -O3 -fPIC -shared lfmt.c
+# macOS
+gcc -o lfmt.so -O3 -fPIC -shared -undefined dynamic_lookup lfmt.c
+# Windows
+cl /Fe lfmt.dll /LD /MT /O2 /DLUA_BUILD_AS_DLL /Ipath/to/lua/include lfmt.c path/to/lua/lib
+```
+
+# Example
+
+```lua
+local fmt = require "fmt"
+
+-- automatic indexed argument
+print(fmt("{} {} {}", 1,2, 3)) --> "1 2 3"
+
+-- manual indexed argument
+print(fmt("{2}, {1}", "World", "Hello")) --> "Hello, World"
+
+-- named indexed argument
+print(fmt("{name} is {type}", { name = "foo", type = "bar" })) --> "foo is bar"
+print(fmt("{t.name} is {t.type}", {t = { name = "foo", type = "bar" }})) --> "foo is bar"
+
+-- format specifier
+print(fmt("{:b}", 42)) --> "101010"
+
+```
+
+## Document
+
+Mostly same as [fmtlib](https://fmt.dev/latest/syntax.html).
+
+Format strings contain “replacement fields” surrounded by curly braces
+`{}`. Anything that is not contained in braces is considered literal
+text, which is copied unchanged to the output. If you need to include
+a brace character in the literal text, it can be escaped by doubling:
+`{{` and `}}`.
+
+The grammar for a replacement field is as follows:
+
+```
+replacement_field ::=  "{" [arg_id] [":" format_spec] "}"
+arg_id            ::=  field_name accessor*
+field_name        ::=  integer | identifier
+accessor          ::=  "." field_name | "[" key_name "]"
+key_name          ::=  field_name | <any chars except ']'>*
+integer           ::=  digit+
+digit             ::=  "0"..."9"
+identifier        ::=  id_start id_continue*
+id_start          ::=  "a"..."z" | "A"..."Z" | "_"
+id_continue       ::=  id_start | digit
+```
+
+the mainly difference is the support of accessor, which is supported
+by Python but not by fmtlib.
+
+- - -
+
+“Format specifications” are used within replacement fields contained
+within a format string to define how individual values are presented.
+Each formattable type may define how the format specification is to be
+interpreted.
+
+Most built-in types implement the following options for format
+specifications, although some of the formatting options are only
+supported by the numeric types.
+
+The general form of a standard format specifier is:
+
+```
+format_spec ::=  [[fill]align][sign]["#"]["0"][width][grouping]["." precision][type]
+fill        ::=  <a character other than '{' or '}'>
+align       ::=  "<" | ">" | "^"
+sign        ::=  "+" | "-" | " "
+width       ::=  integer | "{" [arg_id] "}"
+grouping    ::=  "_" | ","
+precision   ::=  integer | "{" [arg_id] "}"
+type        ::=  int_type | flt_type | str_type
+int_type    ::=  "b" | "B" | "d" | "o" | "x" | "X" | "c"
+flt_type    ::=  "e" | "E" | "f" | "F" | "g" | "G" | "%"
+str_type    ::=  "p" | "s"
+```
+
+Differences (all exists in Python):
+- add grouping support for int_type: `"{:_}"` e.g. `"10_000"`
+- add `"%"` specifier for float type: `"{:%}"` e.g. `"100.0%"`
+
+Lua type vs. type specifiers:
+| Lua Type  | Type specifiers    |
+| --------- | ------------------ |
+| "integer" | `int_type` |
+| "float"   | `flt_type` |
+| Others    | `str_type` |
+
+