diff options
Diffstat (limited to 'lib/pure/pegs.nim')
| -rw-r--r-- | lib/pure/pegs.nim | 133 |
1 files changed, 68 insertions, 65 deletions
diff --git a/lib/pure/pegs.nim b/lib/pure/pegs.nim index 11683bbff..7f0f532fe 100644 --- a/lib/pure/pegs.nim +++ b/lib/pure/pegs.nim @@ -889,7 +889,7 @@ macro mkHandlerTplts(handlers: untyped): untyped = # Transforms the handler spec in *handlers* into handler templates. # The AST structure of *handlers[0]*: # - # .. code-block:: + # ``` # StmtList # Call # Ident "pkNonTerminal" @@ -910,6 +910,7 @@ macro mkHandlerTplts(handlers: untyped): untyped = # StmtList # <handler code block> # ... + # ``` func mkEnter(hdName, body: NimNode): NimNode = template helper(hdName, body) {.dirty.} = template hdName(s, p, start) = @@ -959,60 +960,61 @@ template eventParser*(pegAst, handlers: untyped): (proc(s: string): int) = ## match, else the length of the total match. The following example code ## evaluates an arithmetic expression defined by a simple PEG: ## - ## .. code-block:: nim - ## import std/[strutils, pegs] + ## ```nim + ## import std/[strutils, pegs] ## - ## let - ## pegAst = """ - ## Expr <- Sum - ## Sum <- Product (('+' / '-')Product)* - ## Product <- Value (('*' / '/')Value)* - ## Value <- [0-9]+ / '(' Expr ')' - ## """.peg - ## txt = "(5+3)/2-7*22" + ## let + ## pegAst = """ + ## Expr <- Sum + ## Sum <- Product (('+' / '-')Product)* + ## Product <- Value (('*' / '/')Value)* + ## Value <- [0-9]+ / '(' Expr ')' + ## """.peg + ## txt = "(5+3)/2-7*22" ## - ## var - ## pStack: seq[string] = @[] - ## valStack: seq[float] = @[] - ## opStack = "" - ## let - ## parseArithExpr = pegAst.eventParser: - ## pkNonTerminal: - ## enter: - ## pStack.add p.nt.name - ## leave: - ## pStack.setLen pStack.high - ## if length > 0: - ## let matchStr = s.substr(start, start+length-1) - ## case p.nt.name - ## of "Value": - ## try: - ## valStack.add matchStr.parseFloat - ## echo valStack - ## except ValueError: - ## discard - ## of "Sum", "Product": - ## try: - ## let val = matchStr.parseFloat - ## except ValueError: - ## if valStack.len > 1 and opStack.len > 0: - ## valStack[^2] = case opStack[^1] - ## of '+': valStack[^2] + valStack[^1] - ## of '-': valStack[^2] - valStack[^1] - ## of '*': valStack[^2] * valStack[^1] - ## else: valStack[^2] / valStack[^1] - ## valStack.setLen valStack.high - ## echo valStack - ## opStack.setLen opStack.high - ## echo opStack - ## pkChar: - ## leave: - ## if length == 1 and "Value" != pStack[^1]: - ## let matchChar = s[start] - ## opStack.add matchChar - ## echo opStack + ## var + ## pStack: seq[string] = @[] + ## valStack: seq[float] = @[] + ## opStack = "" + ## let + ## parseArithExpr = pegAst.eventParser: + ## pkNonTerminal: + ## enter: + ## pStack.add p.nt.name + ## leave: + ## pStack.setLen pStack.high + ## if length > 0: + ## let matchStr = s.substr(start, start+length-1) + ## case p.nt.name + ## of "Value": + ## try: + ## valStack.add matchStr.parseFloat + ## echo valStack + ## except ValueError: + ## discard + ## of "Sum", "Product": + ## try: + ## let val = matchStr.parseFloat + ## except ValueError: + ## if valStack.len > 1 and opStack.len > 0: + ## valStack[^2] = case opStack[^1] + ## of '+': valStack[^2] + valStack[^1] + ## of '-': valStack[^2] - valStack[^1] + ## of '*': valStack[^2] * valStack[^1] + ## else: valStack[^2] / valStack[^1] + ## valStack.setLen valStack.high + ## echo valStack + ## opStack.setLen opStack.high + ## echo opStack + ## pkChar: + ## leave: + ## if length == 1 and "Value" != pStack[^1]: + ## let matchChar = s[start] + ## opStack.add matchChar + ## echo opStack ## - ## let pLen = parseArithExpr(txt) + ## let pLen = parseArithExpr(txt) + ## ``` ## ## The *handlers* parameter consists of code blocks for *PegKinds*, ## which define the grammar elements of interest. Each block can contain @@ -1181,8 +1183,7 @@ template `=~`*(s: string, pattern: Peg): bool = ## This calls ``match`` with an implicit declared ``matches`` array that ## can be used in the scope of the ``=~`` call: ## - ## .. code-block:: nim - ## + ## ```nim ## if line =~ peg"\s* {\w+} \s* '=' \s* {\w+}": ## # matches a key=value pair: ## echo("Key: ", matches[0]) @@ -1194,7 +1195,7 @@ template `=~`*(s: string, pattern: Peg): bool = ## echo("comment: ", matches[0]) ## else: ## echo("syntax error") - ## + ## ``` bind MaxSubpatterns when not declaredInScope(matches): var matches {.inject.}: array[0..MaxSubpatterns-1, string] @@ -1230,14 +1231,15 @@ func replacef*(s: string, sub: Peg, by: string): string {. ## Replaces `sub` in `s` by the string `by`. Captures can be accessed in `by` ## with the notation ``$i`` and ``$#`` (see strutils.`%`). Examples: ## - ## .. code-block:: nim + ## ```nim ## "var1=key; var2=key2".replacef(peg"{\ident}'='{\ident}", "$1<-$2$2") + ## ``` ## ## Results in: ## - ## .. code-block:: nim - ## + ## ```nim ## "var1<-keykey; val2<-key2key2" + ## ``` result = "" var i = 0 var caps: array[0..MaxSubpatterns-1, string] @@ -1305,8 +1307,7 @@ func replace*(s: string, sub: Peg, cb: proc( ## The callback proc receives the index of the current match (starting with 0), ## the count of captures and an open array with the captures of each match. Examples: ## - ## .. code-block:: nim - ## + ## ```nim ## func handleMatches*(m: int, n: int, c: openArray[string]): string = ## result = "" ## if m > 0: @@ -1318,12 +1319,13 @@ func replace*(s: string, sub: Peg, cb: proc( ## ## let s = "Var1=key1;var2=Key2; VAR3" ## echo s.replace(peg"{\ident}('='{\ident})* ';'* \s*", handleMatches) + ## ``` ## ## Results in: ## - ## .. code-block:: nim - ## + ## ```nim ## "var1: 'key1', var2: 'Key2', var3: ''" + ## ``` result = "" var i = 0 var caps: array[0..MaxSubpatterns-1, string] @@ -1361,18 +1363,19 @@ iterator split*(s: string, sep: Peg): string = ## Substrings are separated by the PEG `sep`. ## Examples: ## - ## .. code-block:: nim + ## ```nim ## for word in split("00232this02939is39an22example111", peg"\d+"): ## writeLine(stdout, word) + ## ``` ## ## Results in: ## - ## .. code-block:: nim + ## ```nim ## "this" ## "is" ## "an" ## "example" - ## + ## ``` var c: Captures var first = 0 |