gsl-shell.git - gsl-shell

diff --git a/mini-parser.lua b/mini-parser.lua
index b2d7f944..610d2d67 100644
--- a/mini-parser.lua
+++ b/mini-parser.lua

@@ -7,6 +7,7 @@ local mini_lexer_mt = {

__index = mini_lexer,

}

+local literal_chars = {['('] = 1, [')'] = 1, ['~'] = 1, [','] = 1}

local oper_table = {['+'] = 0, ['-'] = 0, ['*'] = 1, ['/'] = 1, ['^'] = 2}

local function new_lexer(src)

@@ -56,7 +57,7 @@ function mini_lexer.next_token(lexer)

lexer:incr()

return {type= 'operator', symbol= c, priority = prio}

end

- if c == '(' or c == ')' then

+ if literal_chars[c] then

lexer:incr()

return {type= c}

end

@@ -71,6 +72,11 @@ function mini_lexer.next_token(lexer)

end

return {type= 'number', value= tonumber(str)}

end

+ msg = { "syntax error in expression:",

+ string.format(' %s', lexer.src),

+ string.format(' %s^', string.rep(' ', lexer.n - 1)) }

+

+ error(table.concat(msg, '\n'))

end

function mini_lexer.next(lexer)

@@ -138,18 +144,37 @@ expr = function(lexer, actions, prio)

return a

end

+local function expr_list(lexer, actions)

+ local a = expr(lexer, actions, 0)

+ local els = actions.exprlist(a)

+ while accept(lexer, ',') > 0 do

+ local b = expr(lexer, actions, 0)

+ els = actions.exprlist(b, els)

+ end

+ return els

+end

+

+local function schema(lexer, actions)

+ local y = expr_list(lexer, actions)

+ expect(lexer, '~')

+ local x = expr_list(lexer, actions)

+ return actions.schema(x, y)

+end

+

local function parse_expr(lexer, actions)

return expr(lexer, actions, 0)

end

local AST_create = {

- infix = function(sym, a, b) return {operator= sym, a, b} end,

- ident = function(id) return {ident= id} end,

- prefix = function(sym, a) return {operator= sym, a} end,

- number = function(x) return {number= x} end,

+ infix = function(sym, a, b) return {operator= sym, a, b} end,

+ ident = function(id) return {ident= id} end,

+ prefix = function(sym, a) return {operator= sym, a} end,

+ number = function(x) return {number= x} end,

+ exprlist = function(a, ls) if ls then ls[#ls+1] = a else ls = {list= true, a} end; return ls end,

+ schema = function(x, y) return {schema= true, x= x, y= y} end,

}

-local format = string.format

+local format, concat = string.format, table.concat

local AST_print

local function is_ident_simple(s)

@@ -171,8 +196,20 @@ local function AST_print_op(e, prio)

end

end

+local function AST_print_exprlist(e)

+ local t = {}

+ for k = 1, #e do t[k] = AST_print(e[k]) end

+ return concat(t, ', ')

+end

+

AST_print = function(e)

- if e.ident then

+ if e.schema then

+ local ys = AST_print_exprlist(e.y)

+ local xs = AST_print_exprlist(e.x)

+ return format("%s ~ %s", ys, xs)

+ elseif e.list then

+ return AST_print_exprlist(e)

+ elseif e.ident then

local s = e.ident

if not is_ident_simple(s) then s = format('[%s]', s) end

return s, 3

@@ -185,4 +222,4 @@ AST_print = function(e)

end

end

-return {lexer = new_lexer, parse = parse_expr, AST= AST_create, print = AST_print}

+return {lexer = new_lexer, schema= schema, parse = parse_expr, AST= AST_create, print = AST_print}