diff options
Diffstat (limited to 'lib/control_flow.nom')
| -rw-r--r-- | lib/control_flow.nom | 122 |
1 files changed, 61 insertions, 61 deletions
diff --git a/lib/control_flow.nom b/lib/control_flow.nom index cfaa7ad..75cf6fd 100644 --- a/lib/control_flow.nom +++ b/lib/control_flow.nom @@ -7,12 +7,12 @@ use "lib/text.nom" use "lib/operators.nom" # No-Op -immediately +immediately: compile [do nothing] to {statements:""} # Conditionals -immediately - compile [if %condition %if_body] to +immediately: + compile [if %condition %if_body] to: %if_body <- (%if_body as lua) return {..} locals: %if_body's "locals" @@ -22,7 +22,7 @@ immediately end parse [unless %condition %unless_body] as: if (not %condition) %unless_body - compile [if %condition %if_body else %else_body, unless %condition %else_body else %if_body] to + compile [if %condition %if_body else %else_body, unless %condition %else_body else %if_body] to: %if_body <- (%if_body as lua) %else_body <- (%else_body as lua) lua> ".." @@ -47,13 +47,13 @@ immediately %when_true_expr if %condition otherwise %when_false_expr %when_false_expr unless %condition else %when_true_expr %when_false_expr unless %condition then %when_true_expr - ..to + ..to: #.. If %when_true_expr is guaranteed to be truthy, we can use Lua's idiomatic equivalent of a conditional expression: (cond and if_true or if_false) if: (%when_true_expr's "type") in {Text:yes, List:yes, Dict:yes, Number:yes} return {..} expr:"(\(%condition as lua expr) and \(%when_true_expr as lua expr) or \(%when_false_expr as lua expr))" - ..else + ..else: #.. Otherwise, need to do an anonymous inline function (yuck, too bad lua doesn't have a proper ternary operator!) To see why this is necessary consider: (random()<.5 and false or 99) @@ -68,20 +68,20 @@ immediately end)() # GOTOs -immediately +immediately: compile [=== %label ===, --- %label ---, *** %label ***] to {..} statements:"::label_\(%label as lua identifier)::;" compile [go to %label] to {..} statements:"goto label_\(%label as lua identifier);" # Basic loop control -immediately +immediately: compile [do next] to {statements:"continue;"} compile [stop] to {statements:"break;"} # Helper function -immediately - compile [if %tree has subtree %subtree where %condition %body] to +immediately: + compile [if %tree has subtree %subtree where %condition %body] to: %body_lua <- (%body as lua) %body_statements <- ((%body_lua's "statements") or "\(%body_lua's "expr");") return {..} @@ -97,22 +97,22 @@ immediately end # While loops -immediately +immediately: compile [do next repeat] to {statements:"goto continue_repeat;"} compile [stop repeating] to {statements:"goto stop_repeat;"} compile [repeat while %condition %body] to %body_lua <- (%body as lua) %body_statements <- ((%body_lua's "statements") or "\(%body_lua's "expr");") - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "do next repeat") ..: %body_statments +<- "\n::continue_repeat::;" %code <- ".." while \(%condition as lua expr) do \%body_statements end --while-loop - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "stop repeating") - .. + ..: %code <- ".." do -- scope of "stop repeating" label \%code @@ -124,7 +124,7 @@ immediately compile [..] repeat %n times %body - ..to + ..to: %body_lua <- (%body as lua) %body_statements <- ((%body_lua's "statements") or "\(%body_lua's "expr");") if %body has subtree % where @@ -134,9 +134,9 @@ immediately for i=1,\(%n as lua expr) do \%body_statements end --numeric for-loop - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "stop repeating") - .. + ..: %code <- ".." do -- scope of "stop repeating" label \%code @@ -145,21 +145,21 @@ immediately return {statements:%code, locals:%body_lua's "locals"} # For loop control flow: -immediately +immediately: compile [stop %var] to {..} statements:"goto stop_\(%var as lua identifier);" compile [do next %var] to {..} statements:"goto continue_\(%var as lua identifier);" # Numeric range for loops -immediately +immediately: compile [..] for %var from %start to %stop by %step %body for %var from %start to %stop via %step %body - ..to + ..to: %body_lua <- (%body as lua) %body_statements <- ((%body_lua's "statements") or "\(%body_lua's "expr");") - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "do next %") and ((3rd in (%'s "value"))'s "value") is (%var's "value") @@ -172,11 +172,11 @@ immediately \%body_statements end --numeric for-loop - if %body has subtree % where - ((%'s "type") = "FunctionCall") and - ((%'s "stub") is "stop %") and + if %body has subtree % where: + ((%'s "type") = "FunctionCall") and: + ((%'s "stub") is "stop %") and: ((2nd in (%'s "value"))'s "value") is (%var's "value") - .. + ..: %code <- ".." do -- scope for stopping for-loop \%code @@ -185,7 +185,7 @@ immediately return {statements:%code, locals:%body_lua's "locals"} -immediately +immediately: parse [for %var from %start to %stop %body] as: for %var from %start to %stop via 1 %body parse [..] for all %start to %stop by %step %body @@ -194,11 +194,11 @@ immediately parse [for all %start to %stop %body] as: for all %start to %stop via 1 %body # For-each loop (lua's "ipairs()") -immediately - compile [for %var in %iterable %body] to +immediately: + compile [for %var in %iterable %body] to: %body_lua <- (%body as lua) %body_statements <- ((%body_lua's "statements") or "\(%body_lua's "expr");") - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "do next %") and ((3rd in (%'s "value"))'s "value") is (%var's "value") @@ -209,11 +209,11 @@ immediately for i,\(%var as lua expr) in ipairs(\(%iterable as lua expr)) do \%body_statements end --foreach-loop - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "stop %") and ((2nd in (%'s "value"))'s "value") is (%var's "value") - .. + ..: %code <- ".." do -- scope for stopping for-loop \%code @@ -224,17 +224,17 @@ immediately parse [for all %iterable %body] as: for % in %iterable %body # Dict iteration (lua's "pairs()") -immediately - compile [for %key = %value in %iterable %body] to +immediately: + compile [for %key = %value in %iterable %body] to: %body_lua <- (%body as lua) %body_statements <- ((%body_lua's "statements") or "\(%body_lua's "expr");") - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "do next %") and ((3rd in (%'s "value"))'s "value") is (%key's "value") ..: %body_statements +<- "\n::continue_\(%key as lua identifier)::;" - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "do next %") and ((3rd in (%'s "value"))'s "value") is (%value's "value") @@ -249,13 +249,13 @@ immediately end --foreach-loop %stop_labels <- "" - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "stop %") and ((2nd in (%'s "value"))'s "value") is (%key's "value") ..: %stop_labels +<- "\n::stop_\(%key as lua identifier)::;" - if %body has subtree % where + if %body has subtree % where: ((%'s "type") = "FunctionCall") and ((%'s "stub") is "stop %") and ((2nd in (%'s "value"))'s "value") is (%value's "value") @@ -269,14 +269,14 @@ immediately return {statements:%code, locals:%body_lua's "locals"} # Switch statement/multi-branch if -immediately - compile [when %body] to +immediately: + compile [when %body] to: %code <- "" %fallthroughs <- [] %locals <- [] %is_first <- (yes) %seen_else <- (no) - for %func_call in (%body's "value") + for %func_call in (%body's "value"): assume ((%func_call's "type") is "FunctionCall") or barf ".." Invalid format for 'when' statement. Only '*' blocks are allowed. with [..] @@ -284,7 +284,7 @@ immediately %star <- (1st in %tokens) %condition <- (2nd in %tokens) %action <- (3rd in %tokens) - .. + ..: assume (=lua "\%star and \%star.type == 'Word' and \%star.value == '*'") or barf ".." Invalid format for 'when' statement. Lines must begin with '*' assume %condition or barf ".." @@ -294,7 +294,7 @@ immediately do next %func_call %action <- (%action as lua) %action_statements <- ((%action's "statements") or "\(%action's "expr");") - for %local in ((%action's "locals") or []) + for %local in ((%action's "locals") or []): lua> "table.insert(\%locals, \%local);" if: =lua "\%condition.type == 'Word' and \%condition.value == 'else'" @@ -304,7 +304,7 @@ immediately else \%action_statements %seen_else <- (yes) - ..else + ..else: assume (not %seen_else) or barf "'else' clause needs to be last in 'when' block" lua> "table.insert(\%fallthroughs, \(%condition as lua expr));" %condition_code <- (%fallthroughs joined with " or ") @@ -323,18 +323,18 @@ immediately return {statements:%code, locals:%locals} # Switch statement -immediately - compile [when %branch_value = ? %body, when %branch_value is ? %body] to +immediately: + compile [when %branch_value = ? %body, when %branch_value is ? %body] to: %code <- "" %fallthroughs <- [] %locals <- [] %is_first <- (yes) %seen_else <- (no) - for %func_call in (%body's "value") + for %func_call in (%body's "value"): assume ((%func_call's "type") is "FunctionCall") or barf ".." Invalid format for 'when' statement. Only '*' blocks are allowed. %tokens <- (%func_call's "value") - with [%star<-(1st in %tokens), %condition<-(2nd in %tokens), %action<-(3rd in %tokens)] + with [%star<-(1st in %tokens), %condition<-(2nd in %tokens), %action<-(3rd in %tokens)]: assume (=lua "\%star and \%star.type == 'Word' and \%star.value == '*'") or barf ".." Invalid format for 'when' statement. Lines must begin with '*' assume %condition or barf ".." @@ -345,7 +345,7 @@ immediately %action <- (%action as lua) %action_statements <- ((%action's "statements") or "\(%action's "expr");") - for %local in ((%action's "locals") or []) + for %local in ((%action's "locals") or []): lua> "table.insert(\%locals, \%local);" if: =lua "\%condition.type == 'Word' and \%condition.value == 'else'" @@ -356,7 +356,7 @@ immediately \%action_statements end %seen_else <- (yes) - ..else + ..else: assume (not %seen_else) or barf "'else' clause needs to be last in 'when % = ?' block" lua> "table.insert(\%fallthroughs, \(%condition as lua expr));" for %i = % in %fallthroughs @@ -386,18 +386,18 @@ immediately return {statements:%code, locals:%locals} # Try/except -immediately +immediately: compile [..] try %action and if it succeeds %success or if it barfs %fallback try %action and if it barfs %fallback or if it succeeds %success - ..to + ..to: %locals <- [] %action_lua <- (%action as lua) %success_lua <- (%success as lua) %fallback_lua <- (%fallback as lua) %fallback <- (%fallback as lua) - for %block in [%action_lua, %success_lua, %fallback_lua] - for %local in ((%block's "locals") or []) + for %block in [%action_lua, %success_lua, %fallback_lua]: + for %local in ((%block's "locals") or []): lua> "table.insert(\%locals, \%local);" lua> "utils.deduplicate(\%locals);" return {..} @@ -418,18 +418,18 @@ immediately return ret; end end - parse [try %action] as + parse [try %action] as: try %action and if it succeeds: do nothing ..or if it barfs: do nothing - parse [try %action and if it barfs %fallback] as + parse [try %action and if it barfs %fallback] as: try %action and if it succeeds: do nothing ..or if it barfs %fallback - parse [try %action and if it succeeds %success] as + parse [try %action and if it succeeds %success] as: try %action and if it succeeds %success or if it barfs: do nothing # Do/finally: -immediately - compile [do %action] to +immediately: + compile [do %action] to: %action <- (%action as lua) return {..} locals: %action's "locals" @@ -438,12 +438,12 @@ immediately \((%action's "statements") or "\(%action's "expr");") end - compile [do %action then always %final_action] to + compile [do %action then always %final_action] to: %action <- (%action as lua) %final_action <- (%final_action as lua) %locals <- [] - for %sub_locals in [%action's "locals", %final_action's "locals"] - for %local in %sub_locals + for %sub_locals in [%action's "locals", %final_action's "locals"]: + for %local in %sub_locals: lua> "table.insert(\%locals, \%local);" lua> "utils.deduplicate(\%locals);" return {..} |