start fixing off-by-one errors: script, block, tuple, args, tup-patt

src/parser.janet

@@ -3,6 +3,9 @@
 ### We still need to scan some things
 (import /src/scanner :as s)
 
+# stash janet type
+(def janet-type type)
+
 (defmacro declare
  "Forward-declares a function name, so that it can be called in a mutually recursive manner."
  [& names]
@@ -75,7 +78,7 @@
  (has-value? terminators ttype))
 
 # breakers are what terminate panics
-(def breaking [:break :newline :semicolon :comma :eof :then :else])
+(def breaking [:break :newline :semicolon :comma :eof :then :else :arrow])
 
 (defn- breaks? 
  "Returns true if the current token in the parser should break a panic"
@@ -89,11 +92,15 @@
  [parser message]
 #  (print "Panic in the parser: " message)
  (def origin (current parser))
- (advance parser)
+ # (advance parser)
  (def skipped @[origin])
  (while (not (breaks? parser))
   (array/push skipped (current parser))
   (advance parser))
+ # but we actually don't want to advance past all breaking tokens
+ # this is the source of the off-by-one errors
+ # only newlines and semicolons should be skipped here; everything else needs to be parsed normaly
+ # wait, except for we don't actually advance past the breaking token
  (array/push skipped (current parser))
  (def err {:type :error :data skipped :token origin :msg message})
  (update parser :errors array/push err)
@@ -279,8 +286,8 @@
  (def origin (current parser))
  (advance parser) # consume the :lparen
  (def ast @{:type :args :data @[] :token origin :partial false})
- (while (separates? parser) (advance parser)) # consume any separators
  (while (not (check parser :rparen))
+  (accept-many parser ;separates)
   (when (check parser :eof)
    (def err {:type :error :token origin :msg "unclosed paren"})
    (array/push (parser :errors) err)
@@ -299,8 +306,7 @@
      {:type :placeholder :token origin}))
    (capture nonbinding parser)))
   (array/push (ast :data) term)
-  (try (separators parser) 
-   ([e] (array/push (ast :data) e))))
+  (capture separators parser))
  (advance parser)
  ast)
 
@@ -337,16 +343,16 @@
  (def origin (current parser))
  (advance parser) # consume the :lparen
  (def ast {:type :tuple :data @[] :token origin})
- (while (separates? parser) (advance parser)) # consume any separators
+ # (while (separates? parser) (advance parser)) # consume any separators
  (while (not (check parser :rparen))
+  (accept-many parser ;separates)
   (when (check parser :eof)
    (def err {:type :error :token origin :msg "unclosed paren"})
    (array/push (parser :errors) err)
    (error err))
   (def term (capture nonbinding parser))
   (array/push (ast :data) term)
-  (try (separators parser) 
-   ([e] (array/push (ast :data) e))))
+  (capture separators parser))
  (advance parser)
  ast)
 
@@ -452,8 +458,8 @@
  (def origin (current parser))
  (advance parser) # consume the :lparen
  (def ast {:type :tuple :data @[] :token origin})
- (while (separates? parser) (advance parser)) # consume any separators
  (while (not (check parser :rparen))
+  (accept-many parser ;separates)
   (when (check parser :eof)
    (def err {:type :error :token origin :msg "unclosed paren"})
    (array/push (parser :errors) err)
@@ -466,8 +472,7 @@
     {:type :splat :data splatted :token origin})
    (capture pattern parser)))
   (array/push (ast :data) term)
-  (try (separators parser) 
-   ([e] (array/push (ast :data) e))))
+  (capture separators parser))
  (advance parser)
  ast)
 
@@ -573,9 +578,12 @@
  (array/push (ast :data) (capture nonbinding parser))
  ast)
 
+(defn- literal-terminator? [token]
+ (def tok-type (token :type))
+ (or (= :newline tok-type) (= :semicolon tok-type)))
+
 (defn- terminator [parser]
  (if-not (terminates? parser) 
-  # this line panics, captures the panic, advances the parser, and re-throws the error; solves an off-by-one error
   (panic parser "expected terminator"))
  (advance parser)
  (while (terminates? parser) (advance parser)))
@@ -798,13 +806,13 @@
 (defn- block [parser]
  (def origin (current parser))
  (expect parser :lbrace) (advance parser)
- (accept-many parser ;terminators)
  (def data @[])
  (while (not (check parser :rbrace))
+  (accept-many parser ;terminators)
   (if (check parser :eof)
    (error {:type :error :token origin :data data :msg "unclosed brace"}))
   (array/push data (capture expr parser))
-  (terminator parser))
+  (capture terminator parser))
  (advance parser)
  {:type :block :data data :token origin})
 
@@ -1103,7 +1111,7 @@
  (def origin (current parser))
  (def lines @[])
  (while (not (check parser :eof))
-  (accept-many parser :newline)
+  (accept-many parser ;terminators)
   (array/push lines (capture toplevel parser))
   (capture terminator parser))
  {:type :script :data lines :token origin})
@@ -1114,13 +1122,35 @@
   (set (parser :ast) ast)
   parser)
 
-# (do
-(comment
+(defn- pp-tok [token]
+ (if (not token) (break "nil"))
+ (def {:line line :lexeme lex :type type :start start} token)
+ (string "<" line "[" start "]" ": " type ": " lex ">"))
+
+(defn- pp-ast [ast &opt indent]
+ (default indent 0)
+ (def {:token token :data data :type type} ast)
+ (def pretty-tok (pp-tok token))
+ (def data-rep (if (= :array (janet-type data))
+  (string "[\n"  
+   (string/join (map (fn [x] (pp-ast x (inc indent))) data) 
+    (string (string/repeat "   " indent) "\n"))
+   "\n" (string/repeat "   " indent) "]")
+  data
+ ))
+ (string (string/repeat "   " indent) type ": " pretty-tok " " data-rep)
+)
+
+(do
+# (comment
 (def source `
-[...x]
+(,,,,,,1, 2, foo, :three)
+
 `)
 (def scanned (s/scan source))
 # (print "\n***NEW PARSE***\n")
 (def a-parser (new-parser scanned))
-(try (def parsed (pattern a-parser)) ([e] (pp e)))
+(def parsed (script a-parser)) 
+(pp (map (fn [err] (err :msg)) ((parse scanned) :errors)))
+(print (pp-ast ((parse scanned) :ast)))
 )