diff options
Diffstat (limited to 'runtime/doc/luaref.txt')
| -rw-r--r-- | runtime/doc/luaref.txt | 110 |
1 files changed, 56 insertions, 54 deletions
diff --git a/runtime/doc/luaref.txt b/runtime/doc/luaref.txt index ecb92d4bb6..0b04005e1a 100644 --- a/runtime/doc/luaref.txt +++ b/runtime/doc/luaref.txt @@ -55,7 +55,6 @@ Lua means "moon" in Portuguese and is pronounced LOO-ah. ============================================================================== 2 THE LANGUAGE *luaref-language* -============================================================================== This section describes the lexis, the syntax, and the semantics of Lua. In other words, this section describes which tokens are valid, how they can be @@ -450,21 +449,22 @@ through an arithmetic progression. It has the following syntax: < The `block` is repeated for `name` starting at the value of the first `exp`, until it passes the second `exp` by steps of the third `exp`. More precisely, -a `for` statement like +a `for` statement like > - `for var =` `e1, e2, e3` `do` `block` `end` + for var = e1, e2, e3 do block end -is equivalent to the code: +< is equivalent to the code: > - `do` - `local` `var, limit, step` `= tonumber(e1), tonumber(e2), tonumber(e3)` - `if not (` `var` `and` `limit` `and` `step` `) then error() end` - `while (` `step` `>0 and` `var` `<=` `limit` `)` - `or (` `step` `<=0 and` `var` `>=` `limit` `) do` - `block` - `var` `=` `var` `+` `step` - `end` - `end` + do + local var, limit, step = tonumber(e1), tonumber(e2), tonumber(e3) + if not ( var and limit and step ) then error() end + while ( step >0 and var <= limit ) + or ( step <=0 and var >= limit ) do + block + var = var + step + end + end +< Note the following: @@ -490,18 +490,18 @@ A `for` statement like `for` `var1, ..., varn` `in` `explist` `do` `block` `end` -is equivalent to the code: - - `do` - `local` `f, s, var` `=` `explist` - `while true do` - `local` `var1, ..., varn` `=` `f(s, var)` - `var` `=` `var1` - `if` `var` `== nil then break end` - `block` - `end` - `end` +is equivalent to the code: > + do + local f, s, var = explist + while true do + local var1, ..., varn = f(s, var) + var = var1 + if var == nil then break end + block + end + end +< Note the following: - `explist` is evaluated only once. Its results are an iterator function, @@ -1871,25 +1871,25 @@ lua_gc *lua_gc()* This function performs several tasks, according to the value of the parameter `what`: - `LUA_GCSTOP` stops the garbage collector. - `LUA_GCRESTART` restarts the garbage collector. - `LUA_GCCOLLECT` performs a full garbage-collection cycle. - `LUA_GCCOUNT` returns the current amount of memory (in Kbytes) in + - `LUA_GCSTOP` stops the garbage collector. + - `LUA_GCRESTART` restarts the garbage collector. + - `LUA_GCCOLLECT` performs a full garbage-collection cycle. + - `LUA_GCCOUNT` returns the current amount of memory (in Kbytes) in use by Lua. - `LUA_GCCOUNTB` returns the remainder of dividing the current + - `LUA_GCCOUNTB` returns the remainder of dividing the current amount of bytes of memory in use by Lua by 1024. - `LUA_GCSTEP` performs an incremental step of garbage collection. + - `LUA_GCSTEP` performs an incremental step of garbage collection. The step "size" is controlled by `data` (larger values mean more steps) in a non-specified way. If you want to control the step size you must experimentally tune the value of `data`. The function returns 1 if the step finished a garbage-collection cycle. - `LUA_GCSETPAUSE` sets `data` /100 as the new value for the + - `LUA_GCSETPAUSE` sets `data` /100 as the new value for the `pause` of the collector (see |luaref-langGC|). The function returns the previous value of the pause. - `LUA_GCSETSTEPMUL` sets `data` /100 as the new value for the + - `LUA_GCSETSTEPMUL`sets `data` /100 as the new value for the `step` `multiplier` of the collector (see |luaref-langGC|). The function returns the previous value of the step multiplier. @@ -2717,20 +2717,22 @@ need "inside information" from the interpreter. lua_Debug *lua_Debug()* - `typedef struct lua_Debug {` - `int event;` - `const char *name; /* (n) */` - `const char *namewhat; /* (n) */` - `const char *what; /* (S) */` - `const char *source; /* (S) */` - `int currentline; /* (l) */` - `int nups; /* (u) number of upvalues */` - `int linedefined; /* (S) */` - `int lastlinedefined; /* (S) */` - `char short_src[LUA_IDSIZE]; /* (S) */` - `/* private part */` - `other fields` - `} lua_Debug;` +> + typedef struct lua_Debug { + int event; + const char *name; /* (n) */ + const char *namewhat; /* (n) */ + const char *what; /* (S) */ + const char *source; /* (S) */ + int currentline; /* (l) */ + int nups; /* (u) number of upvalues */ + int linedefined; /* (S) */ + int lastlinedefined; /* (S) */ + char short_src[LUA_IDSIZE]; /* (S) */ + /* private part */ + other fields + } lua_Debug; +< A structure used to carry different pieces of information about an active function. `lua_getstack` (see |lua_getstack()|) fills only the private part @@ -2739,28 +2741,28 @@ useful information, call `lua_getinfo` (see |lua_getinfo()|). The fields of `lua_Debug` have the following meaning: - `source` If the function was defined in a string, then `source` is +- `source` If the function was defined in a string, then `source` is that string. If the function was defined in a file, then `source` starts with a `@` followed by the file name. - `short_src` a "printable" version of `source`, to be used in error messages. - `linedefined` the line number where the definition of the function starts. - `lastlinedefined` the line number where the definition of the function ends. - `what` the string `"Lua"` if the function is a Lua function, +- `short_src` a "printable" version of `source`, to be used in error messages. +- `linedefined` the line number where the definition of the function starts. +- `lastlinedefined` the line number where the definition of the function ends. +- `what` the string `"Lua"` if the function is a Lua function, `"C"` if it is a C function, `"main"` if it is the main part of a chunk, and `"tail"` if it was a function that did a tail call. In the latter case, Lua has no other information about the function. - `currentline` the current line where the given function is executing. +- `currentline` the current line where the given function is executing. When no line information is available, `currentline` is set to -1. - `name` a reasonable name for the given function. Because +- `name` a reasonable name for the given function. Because functions in Lua are first-class values, they do not have a fixed name: some functions may be the value of multiple global variables, while others may be stored only in a table field. The `lua_getinfo` function checks how the function was called to find a suitable name. If it cannot find a name, then `name` is set to `NULL`. - `namewhat` explains the `name` field. The value of `namewhat` can be +- `namewhat` explains the `name` field. The value of `namewhat` can be `"global"`, `"local"`, `"method"`, `"field"`, `"upvalue"`, or `""` (the empty string), according to how the function was called. (Lua uses the empty string when |