diff options
Diffstat (limited to 'src/lparser.h')
| -rw-r--r-- | src/lparser.h | 53 |
1 files changed, 33 insertions, 20 deletions
diff --git a/src/lparser.h b/src/lparser.h index 62c50cac7cc8..02e9b03aebcb 100644 --- a/src/lparser.h +++ b/src/lparser.h @@ -1,5 +1,5 @@ /* -** $Id: lparser.h,v 1.74 2014/10/25 11:50:46 roberto Exp $ +** $Id: lparser.h,v 1.76 2015/12/30 18:16:13 roberto Exp $ ** Lua Parser ** See Copyright Notice in lua.h */ @@ -13,25 +13,38 @@ /* -** Expression descriptor +** Expression and variable descriptor. +** Code generation for variables and expressions can be delayed to allow +** optimizations; An 'expdesc' structure describes a potentially-delayed +** variable/expression. It has a description of its "main" value plus a +** list of conditional jumps that can also produce its value (generated +** by short-circuit operators 'and'/'or'). */ +/* kinds of variables/expressions */ typedef enum { - VVOID, /* no value */ - VNIL, - VTRUE, - VFALSE, - VK, /* info = index of constant in 'k' */ - VKFLT, /* nval = numerical float value */ - VKINT, /* nval = numerical integer value */ - VNONRELOC, /* info = result register */ - VLOCAL, /* info = local register */ - VUPVAL, /* info = index of upvalue in 'upvalues' */ - VINDEXED, /* t = table register/upvalue; idx = index R/K */ - VJMP, /* info = instruction pc */ - VRELOCABLE, /* info = instruction pc */ - VCALL, /* info = instruction pc */ - VVARARG /* info = instruction pc */ + VVOID, /* when 'expdesc' describes the last expression a list, + this kind means an empty list (so, no expression) */ + VNIL, /* constant nil */ + VTRUE, /* constant true */ + VFALSE, /* constant false */ + VK, /* constant in 'k'; info = index of constant in 'k' */ + VKFLT, /* floating constant; nval = numerical float value */ + VKINT, /* integer constant; nval = numerical integer value */ + VNONRELOC, /* expression has its value in a fixed register; + info = result register */ + VLOCAL, /* local variable; info = local register */ + VUPVAL, /* upvalue variable; info = index of upvalue in 'upvalues' */ + VINDEXED, /* indexed variable; + ind.vt = whether 't' is register or upvalue; + ind.t = table register or upvalue; + ind.idx = key's R/K index */ + VJMP, /* expression is a test/comparison; + info = pc of corresponding jump instruction */ + VRELOCABLE, /* expression can put result in any register; + info = instruction pc */ + VCALL, /* expression is a function call; info = instruction pc */ + VVARARG /* vararg expression; info = instruction pc */ } expkind; @@ -41,14 +54,14 @@ typedef enum { typedef struct expdesc { expkind k; union { + lua_Integer ival; /* for VKINT */ + lua_Number nval; /* for VKFLT */ + int info; /* for generic use */ struct { /* for indexed variables (VINDEXED) */ short idx; /* index (R/K) */ lu_byte t; /* table (register or upvalue) */ lu_byte vt; /* whether 't' is register (VLOCAL) or upvalue (VUPVAL) */ } ind; - int info; /* for generic use */ - lua_Number nval; /* for VKFLT */ - lua_Integer ival; /* for VKINT */ } u; int t; /* patch list of 'exit when true' */ int f; /* patch list of 'exit when false' */ |