TclParser.cc

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#include "TclParser.hh"
#include "ScopedAssign.hh"
#include "ranges.hh"
#include "strCat.hh"
#include <algorithm>
#include <iostream>
#include <cassert>

using std::string;

#if DEBUG_TCLPARSER
void TclParser::DEBUG_PRINT(const string& s)
{
        std::cout << string(2 * level, ' ') << s << '\n';
}

static string_view type2string(int type)
{
        switch (type) {
        case TCL_TOKEN_WORD:
                return "word";
        case TCL_TOKEN_SIMPLE_WORD:
                return "simple word";
        case TCL_TOKEN_EXPAND_WORD:
                return "expand word";
        case TCL_TOKEN_TEXT:
                return "text";
        case TCL_TOKEN_BS:
                return "bs";
        case TCL_TOKEN_COMMAND:
                return "command";
        case TCL_TOKEN_VARIABLE:
                return "variable";
        case TCL_TOKEN_SUB_EXPR:
                return "sub expr";
        case TCL_TOKEN_OPERATOR:
                return "operator";
        default:
                assert(false);
                return {};
        }
}
#endif

static bool inRange(char c, char low, char high)
{
        unsigned t = c - low;
        return t <= unsigned(high - low);
}

static bool isNumber(string_view str)
{
        if (str.starts_with('-') || str.starts_with('+')) {
                str.pop_front();
        }
        if (str.starts_with("0x") || str.starts_with("0X")) {
                str.remove_prefix(2);
                return ranges::all_of(str, [](char c) {
                        return inRange(c, '0', '9') ||
                               inRange(c, 'a', 'f') ||
                               inRange(c, 'A', 'F');
                });
        } else {
                return ranges::all_of(str,
                                      [](char c) { return inRange(c, '0', '9'); });
        }
}


TclParser::TclParser(Tcl_Interp* interp_, string_view input)
        : interp(interp_)
        , colors(input.size(), '.')
        , parseStr(input.str())
        , offset(0)
#if DEBUG_TCLPARSER
        , level(0)
#endif
{
        parse(parseStr.data(), int(parseStr.size()), COMMAND);
}

void TclParser::parse(const char* p, int size, ParseType type)
{
        ScopedAssign<int>    sa1(offset, offset + (p - parseStr.data()));
        ScopedAssign<string> sa2(parseStr, string(p, size));
        last.push_back(offset);

        // The functions Tcl_ParseCommand() and Tcl_ParseExpr() are meant to
        // operate on a complete command. For interactive syntax highlighting
        // we also want to pass incomplete commands (e.g. with an opening, but
        // not yet a closing brace). This loop tries to parse and depening on
        // the parse error retries with a completed command.
        Tcl_Parse parseInfo;
        int retryCount = 0;
        while (true) {
                int parseStatus = (type == EXPRESSION)
                        ? Tcl_ParseExpr(interp, parseStr.data(), int(parseStr.size()), &parseInfo)
                        : Tcl_ParseCommand(interp, parseStr.data(), int(parseStr.size()), 1, &parseInfo);
                if (parseStatus == TCL_OK) break;
                Tcl_FreeParse(&parseInfo);
                ++retryCount;

                bool allowComplete = ((offset + parseStr.size()) >= colors.size()) &&
                                     (retryCount < 10);
                Tcl_Obj* resObj = Tcl_GetObjResult(interp);
                int resLen;
                const char* resStr = Tcl_GetStringFromObj(resObj, &resLen);
                string_view error(resStr, resLen);

                if (allowComplete && error.starts_with("missing close-brace")) {
                        parseStr += '}';
                } else if (allowComplete && error.starts_with("missing close-bracket")) {
                        parseStr += ']';
                } else if (allowComplete && error.starts_with( "missing \"")) {
                        parseStr += '"';
                } else if (allowComplete && error.starts_with("unbalanced open paren")) {
                        parseStr += ')';
                } else if (allowComplete && error.starts_with("missing operand")) {
                        // This also triggers for a (wrong) expression like
                        //    'if { / 3'
                        // and that can't be solved by adding something at the
                        // end. Without the retryCount stuff we would get in an
                        // infinte loop here.
                        parseStr += '0';
                } else if (allowComplete && error.starts_with("missing )")) {
                        parseStr += ')';
                } else {
                        DEBUG_PRINT("ERROR: " + parseStr + ": " + error);
                        setColors(parseStr.data(), int(parseStr.size()), 'E');
                        if ((offset + size) < int(colors.size())) last.pop_back();
                        return;
                }
        }

        if (type == EXPRESSION) {
                DEBUG_PRINT("EXPRESSION: " + parseStr);
        } else {
                if (parseInfo.commentSize) {
                        DEBUG_PRINT("COMMENT: " + string_view(parseInfo.commentStart, parseInfo.commentSize));
                        setColors(parseInfo.commentStart, parseInfo.commentSize, 'c');
                }
                DEBUG_PRINT("COMMAND: " + string_view(parseInfo.commandStart, parseInfo.commandSize));
        }
        printTokens(parseInfo.tokenPtr, parseInfo.numTokens);

        // If the current sub-command stops before the end of the original
        // full command, then it's not the last sub-command. Note that
        // sub-commands can be nested.
        if ((offset + size) < int(colors.size())) last.pop_back();

        const char* nextStart = parseInfo.commandStart + parseInfo.commandSize;
        Tcl_FreeParse(&parseInfo);

        if (type == COMMAND) {
                // next command
                int nextSize = int((parseStr.data() + parseStr.size()) - nextStart);
                if (nextSize > 0) {
                        parse(nextStart, nextSize, type);
                }
        }
}

void TclParser::printTokens(Tcl_Token* tokens, int numTokens)
{
#if DEBUG_TCLPARSER
        ScopedAssign<int> sa(level, level + 1);
#endif
        for (int i = 0; i < numTokens; ) {
                Tcl_Token& token = tokens[i];
                string_view tokenStr(token.start, token.size);
                DEBUG_PRINT(type2string(token.type) + " -> " + tokenStr);
                switch (token.type) {
                case TCL_TOKEN_VARIABLE:
                        assert(token.numComponents >= 1);
                        setColors(tokens[i + 1].start - 1, tokens[i + 1].size + 1, 'v');
                        break;
                case TCL_TOKEN_WORD:
                case TCL_TOKEN_SIMPLE_WORD:
                        if (*token.start == '"') {
                                setColors(token.start, token.size, 'l');
                        }
                        if ((i == 0) && isProc(interp, tokenStr)) {
                                setColors(token.start, token.size, 'p');
                        }
                        break;
                case TCL_TOKEN_EXPAND_WORD:
                        setColors(token.start, 3, 'o');
                        break;
                case TCL_TOKEN_OPERATOR:
                case TCL_TOKEN_BS:
                        setColors(token.start, token.size, 'o');
                        break;
                case TCL_TOKEN_TEXT:
                        if (isNumber(tokenStr) || (*token.start == '"')) {
                                // TODO only works if the same as 'l'
                                setColors(token.start, token.size, 'l');
                        }
                        break;
                }
                if (token.type == TCL_TOKEN_COMMAND) {
                        parse(token.start + 1, token.size - 2, COMMAND);
                } else if (token.type == TCL_TOKEN_SIMPLE_WORD) {
                        ParseType subType = guessSubType(tokens, i);
                        if (subType != OTHER) {
                                parse(tokens[i + 1].start, tokens[i + 1].size, subType);
                        }
                }
                printTokens(&tokens[++i], token.numComponents);
                i += token.numComponents;
        }
}

TclParser::ParseType TclParser::guessSubType(Tcl_Token* tokens, int i)
{
        // heuristic: if previous token is 'if' then assume this is an expression
        if ((i >= 1) && (tokens[i - 1].type == TCL_TOKEN_TEXT)) {
                string_view prevText(tokens[i - 1].start, tokens[i - 1].size);
                if ((prevText == "if") ||
                    (prevText == "elseif") ||
                    (prevText == "expr")) {
                        return EXPRESSION;
                }
        }

        // heuristic: parse text that starts with { as a subcommand
        if (*tokens[i].start == '{') {
                return COMMAND;
        }

        // a plain text element
        return OTHER;
}

bool TclParser::isProc(Tcl_Interp* interp, string_view str)
{
        string command = strCat("openmsx::is_command_name {", str, '}');
        if (Tcl_Eval(interp, command.c_str()) != TCL_OK) return false;
        int result;
        if (Tcl_GetBooleanFromObj(interp, Tcl_GetObjResult(interp), &result)
                != TCL_OK) return false;
        return result != 0;
}

void TclParser::setColors(const char* p, int size, char c)
{
        int start = (p - parseStr.data()) + offset;
        int stop = std::min(start + size, int(colors.size()));
        for (int i = start; i < stop; ++i) {
                colors[i] = c;
        }
}