568a44ef19
return values with either an explicit "return" statement or if they're the only line in the function, and the line is an expression.
311 lines
12 KiB
Plaintext
311 lines
12 KiB
Plaintext
require "lib/metaprogramming.nom"
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require "lib/operators.nom"
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require "lib/utils.nom"
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# Conditionals
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compile [if %condition %if_body] to code: ".."
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if \(%condition as lua) then
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\(%if_body as lua statements)
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end --end if
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parse [unless %condition %unless_body] as: if (not %condition) %unless_body
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parse [if %x == %y %if_body] as: if (%x == %y) %if_body
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parse [if %x != %y %if_body] as: if (%x != %y) %if_body
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parse [unless %x == %y %if_body] as: if (%x != %y) %if_body
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parse [unless %x != %y %if_body] as: if (%x == %y) %if_body
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compile [if %condition %if_body else %else_body, unless %condition %else_body else %if_body] to code: ".."
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if \(%condition as lua) then
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\(%if_body as lua statements)
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else
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\(%else_body as lua statements)
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end --end if
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parse [if %x == %y %if_body else %else_body] as: if (%x == %y) %if_body else %else_body
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parse [if %x != %y %if_body else %else_body] as: if (%x != %y) %if_body else %else_body
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parse [unless %x == %y %if_body else %else_body] as: if (%x != %y) %if_body else %else_body
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parse [unless %x != %y %if_body else %else_body] as: if (%x == %y) %if_body else %else_body
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# Return
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compile [return] to code: "do return; end"
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compile [return %return_value] to code: "do return \(%return_value as lua); end"
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# GOTOs
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compile [-> %label] to code: ".."
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::label_\(nomsu "var_to_lua_identifier" [%label])::;
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compile [go to %label] to code: ".."
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goto label_\(nomsu "var_to_lua_identifier" [%label]);
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rule [tree %tree has function call %call] =:
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lua> ".."
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local target = (\%call).stub;
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for subtree,_ in coroutine.wrap(function() nomsu:walk_tree(\%tree); end) do
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if type(subtree) == 'table' and subtree.type == "FunctionCall"
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and subtree.stub == target then
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return true;
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end
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end
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do return false; end
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# While loops
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compile [do next repeat-loop] to code: "goto continue_repeat;"
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compile [stop repeat-loop] to code: "goto stop_repeat;"
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compile [repeat while %condition %body] to code:
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%continue_labels = (..)
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"\n::continue_repeat::;" if (tree %body has function call \(do next repeat-loop)) else ""
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%code = ".."
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while \(%condition as lua) do
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\(%body as lua statements)\
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..\%continue_labels
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end --while-loop
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if (tree %body has function call \(stop repeat-loop)):
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return ".."
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do --while-loop label scope
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\%code
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::stop_repeat::;
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end --while-loop label scope
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return %code
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parse [repeat %body] as: repeat while (true) %body
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parse [repeat until %condition %body] as: repeat while (not %condition) %body
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parse [repeat while %x == %y %body] as: repeat while (%x == %y) %body
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parse [repeat while %x != %y %body] as: repeat while (%x != %y) %body
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parse [repeat until %x == %y %body] as: repeat while (%x != %y) %body
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parse [repeat until %x != %y %body] as: repeat while (%x == %y) %body
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# For loop control flow:
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compile [stop for-loop] to code: "goto stop_for;"
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compile [stop %var] to code: ".."
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goto stop_\(nomsu "var_to_lua_identifier" [%var]);
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compile [do next for-loop] to code: "goto continue_for;"
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compile [do next %var] to code: ".."
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goto continue_\(nomsu "var_to_lua_identifier" [%var]);
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# Numeric range for loops
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compile [..]
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for %var from %start to %stop by %step %body
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for %var from %start to %stop via %step %body
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..to code:
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%continue_labels = ""
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if (tree %body has function call \(do next for-loop)):
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%continue_labels join= "\n::continue_for::;"
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if (tree %body has function call (tree \(do next %) with {""=%var})):
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%continue_labels join= "\n::continue_\(nomsu "var_to_lua_identifier" [%var])::;"
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# This trashes the loop variables, just like in Python.
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%code = ".."
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for i=\(%start as lua),\(%stop as lua),\(%step as lua) do
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\(%var as lua) = i;
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\(%body as lua statements)\
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..\%continue_labels
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end --numeric for-loop
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%stop_labels = ""
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if (tree %body has function call \(stop for-loop)):
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%stop_labels join= "\n::stop_for::;"
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if (tree %body has function call (tree \(stop %) with {""=%var})):
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%stop_labels join= "\n::stop_\(nomsu "var_to_lua_identifier" [%var])::;"
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if (%stop_labels != ""): ".."
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do --for-loop label scope
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\%code\
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..\%stop_labels
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end --for-loop label scope
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..else: %code
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parse [for %var from %start to %stop %body] as: for %var from %start to %stop via 1 %body
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parse [..]
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for all %start to %stop by %step %body
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for all %start to %stop via %step %body
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..as: for % from %start to %stop via %step %body
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parse [for all %start to %stop %body] as: for all %start to %stop via 1 %body
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compile [for %var in %iterable %body] to code:
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%continue_labels = ""
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if (tree %body has function call \(do next for-loop)):
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%continue_labels join= "\n::continue_for::;"
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if (tree %body has function call (tree \(do next %) with {""=%var})):
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%continue_labels join= "\n::continue_\(nomsu "var_to_lua_identifier" [%var])::;"
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# This trashes the loop variables, just like in Python.
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%code = ".."
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for i,value in ipairs(\(%iterable as lua)) do
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\(%var as lua) = value;
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\(%body as lua statements)\
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..\%continue_labels
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end --foreach-loop
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%stop_labels = ""
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if (tree %body has function call \(stop for-loop)):
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%stop_labels join= "\n::stop_for::;"
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if (tree %body has function call (tree \(stop %) with {""=%var})):
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%stop_labels join= "\n::stop_\(nomsu "var_to_lua_identifier" [%var])::;"
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if (%stop_labels != ""): ".."
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do --for-loop label scope
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\%code\%stop_labels
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end --for-loop label scope
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..else: %code
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parse [for all %iterable %body] as: for % in %iterable %body
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# Dict iteration (lua's "pairs()")
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compile [for %key = %value in %iterable %body] to code:
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%continue_labels = ""
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if (tree %body has function call \(do next for-loop)):
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%continue_labels join= "\n::continue_for::;"
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if (tree %body has function call (tree \(do next %x) with {x=%key})):
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%continue_labels join= "\n::continue_\(nomsu "var_to_lua_identifier" [%key])::;"
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if (tree %body has function call (tree \(do next %) with {""=%value})):
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%continue_labels join= "\n::continue_\(nomsu "var_to_lua_identifier" [%value])::;"
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# This trashes the loop variables, just like in Python.
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%code = ".."
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for key,value in ipairs(\(%iterable as lua)) do
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\(%key as lua), \(%value as lua) = key, value;
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\(%body as lua statements)\
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..\%continue_labels
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end --foreach-loop
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%stop_labels = ""
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if (tree %body has function call \(stop for-loop)):
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%stop_labels join= "\n::stop_for::;"
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if (tree %body has function call (tree \(stop %) with {""=%key})):
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%stop_labels join= "\n::stop_\(nomsu "var_to_lua_identifier" [%key])::;"
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if (tree %body has function call (tree \(stop %) with {""=%value})):
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%stop_labels join= "\n::stop_\(nomsu "var_to_lua_identifier" [%value])::;"
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if (%stop_labels != ""): ".."
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do --for-loop label scope
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\%code\
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..\%stop_labels
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end --for-loop label scope
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..else: %code
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# Switch statement/multi-branch if
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compile [when %body] to code:
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%result = ""
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%fallthroughs = []
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%first = (yes)
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for %func_call in (%body's "value"):
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assert ((%func_call's "type") == "FunctionCall") ".."
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Invalid format for 'when' statement. Only '*' blocks are allowed.
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%tokens = (%func_call's "value")
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%star = (%tokens -> 1)
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assert (=lua "\%star and \%star.type == 'Word' and \%star.value == '*'") ".."
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Invalid format for 'when' statement. Lines must begin with '*'
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%condition = (%tokens -> 2)
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assert %condition ".."
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Invalid format for 'when' statement. Lines must begin with '*' and have a condition or the word "else"
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%action = (%tokens -> 3)
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if (%action == (nil)):
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lua do> "table.insert(\%fallthroughs, \%condition)"
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do next %func_call
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if (=lua "\%condition.type == 'Word' and \%condition.value == 'else'"):
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%result join= ".."
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else
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\(%action as lua statements)
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stop for-loop
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..else:
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%condition = (%condition as lua)
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for all %fallthroughs:
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%condition join= " or \(% as lua)"
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%result join= ".."
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\("if" if %first else "elseif") \%condition then
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\(%action as lua statements)
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%fallthroughs = []
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%first = (no)
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if (%result != ""):
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%result join= "\nend"
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return %result
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# Switch statement
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compile [when %branch_value == ? %body] to code:
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%result = ""
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%fallthroughs = []
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%first = (yes)
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for %func_call in (%body's "value"):
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assert ((%func_call's "type") == "FunctionCall") ".."
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Invalid format for 'when' statement. Only '*' blocks are allowed.
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%tokens = (%func_call's "value")
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%star = (%tokens -> 1)
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assert (=lua "\%star and \%star.type == 'Word' and \%star.value == '*'") ".."
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Invalid format for 'when' statement. Lines must begin with '*'
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%condition = (%tokens -> 2)
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assert %condition ".."
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Invalid format for 'when' statement. Lines must begin with '*' and have a condition or the word "else"
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%action = (%tokens -> 3)
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if (%action == (nil)):
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lua> "table.insert(\%fallthroughs, \%condition)"
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do next %func_call
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if (=lua "\%condition.type == 'Word' and \%condition.value == 'else'"):
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%result join= ".."
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else
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\(%action as lua statements)
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stop for-loop
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..else:
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%condition = "branch_value == (\(%condition as lua))"
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for all %fallthroughs:
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%condition join= " or (branch_value == \(% as lua))"
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%result join= ".."
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\("if" if %first else "elseif") \%condition then
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\(%action as lua statements)
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%fallthroughs = []
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%first = (no)
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if (%result != ""):
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%result = ".."
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do --when == ?
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local branch_value = \(%branch_value as lua);\
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..\%result
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end
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end --when == ?
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return %result
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# Try/except
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compile [..]
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try %action and if it succeeds %success or if it fails %fallback
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try %action and if it fails %fallback or if it succeeds %success
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..to code: ".."
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do
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local fell_through = false;
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local ok, ret1, ret2 = pcall(function(nomsu, vars)
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\(%action as lua statements)
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fell_through = true;
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end, nomsu, vars);
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if ok then
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\(%success as lua statements)
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end
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if not ok then
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\(%fallback as lua statements)
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elseif not fell_through then
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return ret1, ret2;
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end
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end
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parse [try %action] as:
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try %action and if it succeeds: pass
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..or if it fails: pass
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parse [try %action and if it fails %fallback] as:
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try %action and if it succeeds: pass
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..or if it fails %fallback
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parse [try %action and if it succeeds %success] as:
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try %action and if it succeeds %success or if it fails: pass
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# Do/finally:
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compile [do %action then always %final_action] to code: ".."
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do
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local fell_through = false;
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local ok, ret1, ret2 = pcall(function(nomsu, vars)
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\(%action as lua statements)
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fell_through = true;
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end, nomsu, vars);
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local ok2, _ = pcall(function(nomsu, vars)
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\(%final_action as lua statements)
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end, nomsu, vars);
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if not ok then nomsu:error(ret1); end
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if not ok2 then nomsu:error(ret2); end
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if not fell_through then
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return ret1, ret2;
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end
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end
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